Graphite room temperature superconductor

Abstract

To provide a superconductor having a superconducting transition temperature (critical temperature; Tc) of at least room temperature (280K to 310K) at ambient pressure (0.08 to 0.12 MPa).SOLUTION: A superconductor device includes a graphite structure 100, a first electrode 110, a second electrode 120, and a wrinkle region 112. The graphite structure includes a topmost layer 102 including at least one topmost atomic layer. The first electrode is arranged over the at least one topmost atomic layer. The second electrode is arranged over the at least one topmost atomic layer and spaced apart from the first electrode. The wrinkle region is included in the at least one topmost atomic layer. The wrinkle region is arranged between the first electrode and the second electrode and includes a plurality of wrinkles 114 with a pair of wrinkles. The first electrode and the second electrode both electrically contact both wrinkles of the pair. A distance between the wrinkles of the pair is 0.2 μm or less.SELECTED DRAWING: Figure 3e

Description

[Technical Field]

[0001] The present disclosure relates to high (critical) temperature superconductors, particularly graphite-based high (critical) temperature superconductors that utilize folds in the top graphite layer near the surface or interface. [Background technology]

[0002] Superconductivity is a phenomenon observed in materials characterized by the disappearance of the material's zero resistance, i.e., electrical resistance state, and the emission of magnetic fields from the material. Materials that exhibit these properties are called superconductors. In actual experiments, superconductivity is typically identified as dissipative (i.e., lossless) electrical current passing through a material, i.e., the energy loss associated with current transport is much lower than in conventional non-superconducting materials. This phenomenon was discovered in 1911 for mercury (Hg), which becomes superconducting below its superconducting transition temperature (Tc) of 4.2 K, also known as the critical temperature. Below Tc, mercury exhibits superconductivity; above Tc, mercury behaves like a conventional material with the resistivity of conventional mercury. Experiments have shown that when a superconducting material is heated from a temperature below Tc to a temperature above Tc, its resistance jumps from zero to a finite (i.e., much larger) value at the superconducting transition temperature, Tc. Since this discovery, the constant search for materials that exhibit superconductivity at higher, elevated Tc continues.

[0003] Superconductivity in materials with a critical temperature above 20 K is called high-temperature (critical) superconductivity (HTC). The discovery of HTC in Ba-La-Cu-O cuprates with Tc ~ 30 K (see J.G.Bednorz and K.A.Muller, Z.Phys.B 64, 189 (1986)) and Y-Ba-Cu-O with Tc as high as 93 K (see M.K.Wu et al., Phys.Rev.Lett. 58, 908 (1987)) led to the development of superconductivity at ambient conditions (280 K - 310 K, 10 K), also referred to as "room-temperature superconductivity" (RTS). 5This is thought to have resulted in superconductivity at 30 GPa, sparking a race to develop materials that exhibit RTS. To date, the highest ambient pressure Tc = 135 K has been achieved for HgBa2Ca2Cu3O9 (see A. Schilling et al., Nature 363, 56 (1993)), and Tc increased to 164 K at 30 GPa (see L. Gao et al., Phys. Rev. B 50, 4260 (1994)).

[0004] Outside of the cuprates, bulk superconductivity with the highest Tc=33 K at ambient pressure has been observed in alkali-doped buckminsterfullerene, CsxRbyC60 (see K. Tanigaki, Nature 352, 222 (1991)).

[0005] Very recently, a zero-resistivity state near room temperature has been reported for various hydride systems under pressures P > 200 GPa (for a review, see G. Gao et al., Materials Today Physics 100546 (2021) forthcoming).

[0006] Graphite is another promising material in the RTS race. Bulk superconductivity was first discovered in the alkali metal graphite intercalation compound C8K (see N.B. Hannay et al., Phys. Rev. Lett. 14, 225 (1965)) at a superconducting transition temperature Tc = 0.15 K, followed 40 years later by bulk superconductivity in C6Yb (see T.E. Weller et al., Nature Physics 1, 39 (2005)) at Tc = 6.5 K and C6Ca (see N. Emery et al., Phys. Rev. Lett. 95, 087003 (2005)) at Tc = 11.5 K. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] J.G. Bednorz and K.A. Muller, Z. Phys. B 64, 189 (1986)

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Non-Patent Document 8

Non-Patent Document 9

Summary of the Invention

Problems to be Solved by the Invention

[0008] In view of the above technical problems, there is a need for a superconductor that has a superconducting transition temperature (critical temperature; Tc) of at least room temperature (280 K to 310 K), preferably at ambient pressure (0.08 to 0.12 MPa). In the context of the present disclosure, the term superconductor refers to a device adapted to transport essentially dissipative electrical current (in other words, exhibiting a zero-resistance state or a vanishing (electrical) resistance state, respectively). An essentially dissipative electrical current can be characterized by a resistance or resistivity that is at least 100 times less than the resistance or resistivity of a similar device (e.g., having a similar or identical material composition, particularly the same device) in a non-superconducting state (e.g., above the critical temperature and / or not exhibiting all the structural features of the claimed subject matter). [Means for solving the problem]

[0009] This object is achieved by a superconducting device according to claim 1. Claim 14 provides for the use of a graphite structure as a superconducting device. Claim 15 relates to a method for manufacturing a superconducting device. The dependent claims relate to preferred embodiments.

[0010] In a first aspect, a superconducting device includes a graphite structure, a first electrode, a second electrode, and a corrugated region. The graphite structure includes at least one top atomic layer. The first electrode is disposed on the at least one top atomic layer. The second electrode is disposed on the at least one top atomic layer and spaced apart from the first electrode. The corrugated region is included within the at least one top atomic layer. The corrugated region is disposed between the first electrode and the second electrode and includes a plurality of corrugations, including pairs of corrugations. Both the first electrode and the second electrode are in electrical contact with both corrugations of the pair. The distance between the corrugations of the pair is 0.2 μm or less.

[0011] The superconducting device can exhibit a zero-resistance state above room temperature and ambient pressure. The zero-resistance state can be considered a property of superconductivity, and within the context of this disclosure, can be considered a defining characteristic of superconductivity. The zero-resistance state of the superconducting device has been demonstrated and proven in various experiments, which will be described in detail throughout this disclosure. Thus, the superconducting device can implement the long-sought room-temperature superconductor. The zero-resistance state can open up numerous applications related to, for example, quantum computing using room-temperature superconductors, or dissipationless current and information transmission in other conventional electronic devices, such as integrated semiconductor electronics.

[0012] The zero-resistance state (and thus the superconductor / superconducting / superconducting device according to the present disclosure) can be distinguished from local (microscopic) superconductivity implemented in materials that exhibit some of the properties associated with conventional superconductivity but not with the zero-resistance state.

[0013] Previous experimental results may be related to localized microscopic superconductivity in small volume fractions of graphite at temperatures as high as 300 K (see, e.g., Y. Kopelevich et al., J. Low Temp. Phys. 119, 691 (2000); R.R. da Silva et al., Phys. Rev. Lett. 87, 14700 (2001); N.P. Yang et al., Chin. Phys. Lett. 18, 1648 (2001); S. Moehlecke et al., Phil. Mag. B 82, 1335 (2002); Y. Kawashima, AIP Advances 3, 052132 (2013); Y. Kopelevich et al., Physica C 514, 237 (2015)). In particular, several decades ago, Antonowicz measured Josephson-type oscillations and Shapiro-like steps in the IV characteristics at room temperature in Al-AC-Al sandwiches (AC = amorphous carbon) (see K. Antonowicz, Nature 247, 358 (1974); Phys. Status Solidi A 28, 497 (1975)). To elaborate on some of the other examples, magnetization measurements of both sulfur (S)-doped AC (see I. Felner et al., Phys. Rev. B 79, 233409 (2009)) and S-doped graphite (R.R. da Silva et al., Phys. Rev. Lett. 87, 14700 (2001); N.P. Yang et al., Chin. Phys. Lett. 18, 1648 (2001); S. Moehlecke et al., Phil. Mag. B 82, 1335 (2002)) show local superconductivity with nearly the same maximum Tc of about 38 K. Because AC consists of curved graphene and / or fullerene-like fragments (see P.J.F. Harris et al., Phil. Mag. Lett. 80, 381 (2000)), it is hypothesized that similar structural defects in graphite may be responsible for the high-temperature local superconductivity.So far, efforts to achieve a zero-resistance state in graphite have been unsuccessful (see, for example, A. Ballestar et al., Carbon 72, 312 (2014); PDE Esquinazi et al., Quantum Stud.: Math. Found. 5, 41 (2018)).

[0014] The zero-resistance state of a superconducting device, also referred to as global superconductivity in the context of this disclosure, can be associated with current transport along the direction of the continuous, electronically coupled folds of the top graphite layer. Electronic coupling can be ensured by using folds with a spacing (distance) within a critical value of approximately 0.2 μm. Electrodes can be used to contact (identical) folds at different locations to induce and extract supercurrent through the electronically coupled folds. This arrangement can be considered important for the implementation of superconducting devices.

[0015] The distance between pairs of plications may refer to the minimum distance between pairs of plications.

[0016] Alternatively or additionally, the distance between pairs of folds may refer to the average distance between pairs of folds.

[0017] Alternatively or additionally, the distance between pairs of folds may refer to the maximum distance between the pairs of folds.

[0018] The distance between the pair of folds may be at most 0.15 μm, in particular at most 0.1 μm.

[0019] Alternatively or additionally, each of the plurality of folds may include an average distance to a respective adjacent fold. The average fold distance may be defined by the average of the average distances of all of the plurality of folds. The average fold distance may be at most 0.2 μm, particularly at most 0.15 μm or at most 0.1 μm.

[0020] The folds of a pair may be adjacent folds, and in particular the (minimum) distance between the folds of a pair may be less than or equal to a second fold distance between any fold and any other fold of the pair.

[0021] Pairs of plications may form bifurcations and / or intersections. In particular, at least 10 plications of the plurality of plications and their respective adjacent plications may form bifurcations and / or intersections. In particular, at least one-quarter of the plurality of plications and their respective adjacent plications may form bifurcations and / or intersections, or all plications of the plurality of plications and their respective adjacent plications may form bifurcations and / or intersections.

[0022] The branches and / or intersections can beneficially enhance the electronic coupling between the corrugations and increase the critical temperature of the superconducting device. For enhancement, not all corrugations need to be branches or intersections; even if a small fraction of the corrugations are branches or intersections, it can be beneficial.

[0023] The superconducting device may be adapted to support a superconducting current and / or an essentially dissipationless current between the first electrode and the second electrode, particularly, the superconducting device may be adapted to support a superconducting current and / or an essentially dissipationless current between the first electrode and the second electrode through the folded region.

[0024] The superconducting device may be adapted to support superconducting and / or essentially dissipationless current flow between the first and second electrodes at a temperature in the crease region of at least 100K, particularly at least 140K, particularly at least 180K, particularly at least 220K, particularly at least 260K, particularly at least 300K, particularly at least 300K or room temperature.

[0025] Superconducting and / or essentially dissipative current may particularly refer to current flow between the first and second electrodes through a folded region having a resistivity that is at least 10 times lower than the bulk resistivity of graphite, particularly at least 20 times lower than the bulk resistivity of graphite, particularly at least 30 times lower than the bulk resistivity of graphite, or at least 50 times lower than the bulk resistivity of graphite, particularly at least 100 times lower than the bulk resistivity of graphite, particularly at least 500 times lower than the bulk resistivity of graphite, particularly at least 1000 times lower than the bulk resistivity of graphite, or at least 5000 times lower than the bulk resistivity of graphite, for example, less than 1 μΩ / meter at room temperature, or less than 0.1 μΩ / meter at room temperature.

[0026] Bulk resistivity of graphite may refer to the resistivity of pure graphite, especially the resistivity of graphite containing less than 3% (by atomic number) metal intercalates, such as alkali metal intercalates.

[0027] Room temperature may refer to a temperature in the range of 280K to 310K.

[0028] The superconducting device can be adapted to support a current between the first electrode and the second electrode through the folded region having a resistivity at least 100 times lower than the bulk resistivity of graphite, with the folded region at room temperature.

[0029] The fold area is at least 10 when the voltage between the first electrode and the second electrode is at most 10 nV. 6 A / cm 2 The present invention can be adapted to support a current density between the first electrode and the second electrode through the folded region of at least 10. In particular, the current density between the first electrode and the second electrode through the folded region can be at least 10. 6 μA / cm 2 , especially at least 10 7 A / cm 2 may be.

[0030] The twin folds may include parallel sections.

[0031] The parallel sections may correspond to sections where the distance between pairs of pleats is minimal.

[0032] The parallel sections may extend along at least 20% of the extent of each of the pairs of folds between the first and second electrodes, in particular along at least 40% of the extent of each of the pairs, in particular along at least 60% of the extent of each of the pairs, in particular along at least 80% of the extent of each of the pairs, or along the entire extent of each of the pairs.

[0033] The parallel sections of the folds can beneficially strengthen their electronic coupling and thus increase the critical temperature of the superconducting device.

[0034] The graphite structure may comprise or consist of graphite comprising atomic layers, which may include at least one top atomic layer.

[0035] Each atomic layer of the plurality of atomic layers may be a carbon atom layer. In particular, each atomic layer of the plurality of atomic layers may correspond to a graphene layer.

[0036] The ratio of the resistivity of the graphite along a direction perpendicular to the atomic layers to the resistivity along the atomic layers may be at least 20,000, particularly at least 25,000, particularly at least 50,000 or at least 100,000. The resistivity of the graphite along a direction perpendicular to the atomic layers may refer to a temperature of the graphite of 300 K. The resistivity of the graphite along a direction perpendicular to the atomic layers and the resistivity of the graphite along the atomic layers may refer to a section of graphite without continuous folded regions or without any folded regions at all.

[0037] The graphite structure may include at least one bulk atomic layer below the at least one top atomic layer, and the at least one bulk atomic layer may be included in the plurality of atomic layers.

[0038] In particular, the at least one bulk atomic layer may comprise at least two bulk atomic layers, in particular at least three bulk atomic layers, in particular at least four bulk atomic layers, in particular at least five bulk atomic layers, in particular at least six bulk atomic layers, in particular at least eight bulk atomic layers, in particular at least 10 bulk atomic layers, in particular at least 20 bulk atomic layers or at least 50 atomic layers.

[0039] Experiments suggest that electronic coupling can be mediated by bulk atomic layers below the top atomic layer. Therefore, bulk atomic layers can beneficially increase the critical temperature of superconducting devices. In particular, the use of bulk atomic layers (or bulk graphite, respectively) of a particular quality can beneficially increase the critical temperature of superconducting devices. The ratio between the resistivity of graphite along the direction perpendicular to the atomic layers and the resistivity along the atomic layers can be considered a direct characteristic of the quality of the bulk atomic layers (or bulk graphite, respectively).

[0040] The at least one top atomic layer may comprise at least 2 atomic layers, in particular at least 3 atomic layers, in particular at least 4 atomic layers, in particular at least 5 atomic layers, in particular at least 6 atomic layers, in particular at least 7 atomic layers, in particular at least 8 atomic layers, in particular at least 9 atomic layers, in particular at least 10 atomic layers, in particular at least 100 atomic layers or at least 1000 atomic layers.

[0041] Each bulk atomic layer can include a c-axis perpendicular to the bulk atomic layer.

[0042] The c-axes of all bulk atomic layers may be aligned, for example, to within 3°, particularly within 2°, particularly within 1°, particularly within 0.5°, particularly within 0.3° or within 0.2°.

[0043] Experiments have shown that the alignment of the c-axis of the bulk atomic layer can be considered as another characteristic of the quality of the bulk atomic layer (or bulk graphite, respectively).

[0044] The graphite may include or be highly oriented pyrolytic graphite.

[0045] At least a section of the graphite structure may include a vernal lamination. In particular, at least a section of at least one top atomic layer may include a vernal lamination. In particular, at least a section of at least one top atomic layer in a region between the folds of the plurality of folds may include a vernal lamination. Alternatively or additionally, at least one bulk atomic layer may include a vernal lamination.

[0046] At least a portion of the graphite structure may comprise rhombohedral stacking, particularly at least a portion of at least one top atomic layer may comprise rhombohedral stacking.

[0047] At least one of the plurality of corrugations may include a section having rhombohedral lamination and, optionally, a section having vernal lamination. In particular, most and all of the plurality of corrugations may each include a section having rhombohedral lamination and, optionally, a section having vernal lamination.

[0048] The change in the stacking of atomic layers at / within the folds can be considered as one of the origins of superconductivity arising from the folds, which may be the origin of the zero resistance state.

[0049] The at least one top atomic layer may include at least one flat section between at least one pair of the plurality of folds or between any pair of the plurality of folds. In particular, the at least one flat section may include or be a section or any section within the fold region having a surface corrugation smaller than the average surface corrugation associated with the folds and / or a curvature smaller than the average maximum curvature of the folds. For example, the at least one flat section may include a surface corrugation of at most 3 nm, in particular at most 1 nm or at most 0.5 nm.

[0050] The term surface can refer to the interface of graphite to a vacuum, a gas (such as air), a liquid (such as an electrolyte), or another solid.

[0051] Each of the at least one uppermost atomic layer in the at least one flat section can have a c-axis perpendicular to the flat section, and the c-axes of all of the at least one uppermost atomic layer in the at least one flat section can be aligned, for example, within 3°, particularly within 2°, particularly within 1°, or within 0.5°.

[0052] At least one flat section can define a surface. For example, the surface can be parallel to or defined by a plane in which the at least one flat section extends. In embodiments in which the at least one flat section includes at least three flat sections, the surface can alternatively or additionally be defined as a surface connecting the at least three flat sections.

[0053] Any of the plurality of pleats may include an elongated shape.

[0054] A fold included in the pair(s) of folds or folds may include or be a curved section of at least one top atomic layer, in particular the curved section of at least one top atomic layer may be curved away from the surface and / or curved away from a flat section.

[0055] A fold included in the pair(s) of folds or folds may include or be a fold of at least one top atomic layer, in particular a fold of at least one top atomic layer that is a fold away from the surface and / or a fold away from the flat section.

[0056] A fold included in the pair(s) of folds or folds may comprise or be a protrusion of at least one top atomic layer from at least one flat section, in particular a protrusion away from the surface and / or a protrusion away from the flat section.

[0057] The at least one flat section may include a first flat section and a second flat section, and any fold of the plurality of folds may refer to a curved section of at least one top atomic layer between the first and second flat sections, and / or a bent portion of at least one top atomic layer between the first and second flat sections, and / or a protruding portion of at least one top atomic layer between the first and second flat sections.

[0058] The pair of folds may have a distance between the first and second electrodes of up to 0.2 μm along the majority of their respective lengths.

[0059] The pair of plications may include straight line segments, or the pair of plications may include respective straight line segments.

[0060] The straight line segment(s) may extend along at least 30% of the length(s) of the fold(s) between the first and second electrodes, in particular along at least 50% of the length(s) of the fold(s), in particular along at least 70% of the length(s) of the fold(s), in particular along at least 90% of the length(s) of the fold(s), or along the entire length(s) of the fold(s).

[0061] The straight line segment(s) may extend along a respective straight line segment direction. The direction of the straight line segment(s) may be perpendicular to the first edge and / or perpendicular to the second edge. The direction of the straight line segment(s) may be parallel to the surface.

[0062] The straight line segments of the pair of pleats may include or be parallel sections.

[0063] The distance between pairs of plications may refer to the distance between parallel sections of the pair of plications, particularly the distance between parallel straight line segments of the pair of plications.

[0064] The twin folds or parallel sections of the twin folds may have a length, especially within the fold region, of at least 0.05 mm, especially at least 0.1 mm, especially at least 0.2 mm, especially at least 0.3 mm or at least 0.4 mm.

[0065] The width of the pleated region may refer to the minimum extent of the pleated region along a direction perpendicular to the direction connecting the first electrode and the second electrode, or alternatively, the width of the pleated region may refer to the average extent of the pleated region along a direction perpendicular to the direction connecting the first electrode and the second electrode.

[0066] The first electrode may have a first edge that defines a cross section of the boundary of the fold region.

[0067] The second electrode may have a second edge that defines a second cross section of the boundary of the fold region, and the second edge may be parallel or concentric with the first edge.

[0068] The width of the pleated region may refer to the extent of the pleated region along a direction parallel to or concentric with the first edge or the second edge. In particular, the width of the pleated region may refer to the minimum or average extent of the pleated region along a direction parallel to the first edge or the second edge.

[0069] The first electrode and / or the second electrode may be in direct physical contact with at least one top atomic layer, in particular directly above at least one top atomic layer, and in particular the first electrode and / or the second electrode may be in direct physical contact with a pair of folds.

[0070] The second electrode may be displaced relative to the first electrode along the at least one top atomic layer, and may be at the same height or a different height than the first electrode along a vertical direction perpendicular to the at least one top atomic layer and / or the surface.

[0071] One or both corrugations of the pair may extend along a first corrugation direction near the first electrode and / or at its(their) respective contact(s) to the first electrode. In particular, the corrugations may be essentially straight along the first corrugation direction near the first electrode. A geometry in which the corrugations abut the edge of the electrode(s) at a 90° angle (perpendicular) may be beneficial for driving superconducting / dissipationless current through the superconducting device and for extracting superconducting / dissipationless current.

[0072] The first edge may be perpendicular to the first pleat direction. The first electrode may contact the pleats at an angle of essentially 90° between the first edge and the first pleat direction, and may particularly contact at least 20% of the pleats, particularly at least 30%, particularly at least 40% or at least 50% of the pleats at an angle of essentially 90° between the first edge and the first pleat direction.

[0073] One or both folds of the pair may extend along a second fold direction in the vicinity of the second electrode and / or at its(their) respective contact(s) to the second electrode(s). In particular, the folds may be essentially straight along the second fold direction in the vicinity of the first electrode.

[0074] The pair of folds may extend along a second fold direction in the vicinity of the second electrode.

[0075] The second edge may be perpendicular to the second pleat direction.

[0076] The length of the pleated region between the first and second electrodes may be at least 0.5 μm, particularly at least 1 μm, particularly at least 0.01 mm, particularly at least 0.05 mm, particularly at least 0.1 mm, particularly at least 0.2 mm, particularly at least 1 mm, particularly at least 10 mm, particularly at least 100 mm or at least 200 mm.

[0077] The width of the pleated region may be at least 1 μm, in particular at least 2 μm or at least 50 μm.

[0078] The plurality of pleats may comprise at least 3 pleats, particularly at least 4 pleats, particularly at least 5 pleats, particularly at least 10 pleats, particularly at least 100 pleats or at least 1000 pleats.

[0079] The plurality of pleats may include a dense pleat array having at least one pleat.

[0080] The plurality of folds may include adjacent folds and opposite adjacent folds of at least one fold of the dense fold array on opposite sides thereof, and the distance between the at least one fold and the adjacent fold and the distance between the at least one fold and the opposite adjacent fold may both be at most 0.2 μm.

[0081] The dense fold array can maximize electronic coupling, thus increasing the critical temperature of the superconducting device because every dense fold can couple to at least two adjacent folds on opposite sides of it. In particular, the dense fold array (dense folds) does not contain major sections of unfolded fold region that may not contribute to dissipation current.

[0082] At least one plication, an adjacent plication, and / or an opposite adjacent plication may be characterized by the features disclosed above in the context of a plication.

[0083] The distance between at least one plication and an adjacent (opposite) plication may be characterized by the features disclosed above in the context of the distance between pairs of plications.

[0084] The dense fold array may comprise at least two folds, in particular at least three folds, in particular at least four folds, in particular at least five folds, in particular at least six folds, in particular at least seven folds, or at least eight folds characterized by the features described above in the context of at least one fold.

[0085] The adjacent fold or the opposite adjacent fold may be a fold of a dense fold array.

[0086] The dense pleat array may be continuous and / or may not include any flat sections having a width greater than 0.2 μm.

[0087] The minimum distance between any fold in the dense fold array and any nearest fold in the dense fold array must not exceed 0.2 μm (for both (reference) sides of the fold). The nearest fold may be a fold in the dense fold array on the reference side of the fold that has a smaller minimum distance to the fold than the minimum distance between the fold and any other fold in the dense fold array on the reference side of the fold.

[0088] The at least one top atomic layer and / or the plurality of folds may comprise at least two dense fold arrays, in particular at least three dense fold arrays, in particular at least five dense fold arrays, in particular at least ten dense fold arrays or at least 100 dense fold arrays.

[0089] At least a segment of a pair of pleats and / or at least a segment of pleats in a dense pleat array(s) or at least a segment of pleats included in a plurality of pleats may be oriented along a common pleat direction. When pleats are oriented (at least in part) along the same common pleat direction, the parallelism of the pleats, and therefore the electronic coupling between the pleats, and ultimately the critical temperature of the superconducting device, can be further improved.

[0090] In particular, the folds included in a fold or folds of a pair of folds and / or dense fold array(s) may be oriented along a common fold direction along a majority of their respective extents between the first and second electrodes, and in particular, the folds included in a fold or folds of a pair of folds and / or dense fold array(s) may be oriented along a common fold direction along the entirety of their respective extents between the first and second electrodes.

[0091] The common fold direction may be parallel to or coincident with a line connecting the first and second electrodes.

[0092] The common pleat direction may be perpendicular to the width of the pleated region and / or perpendicular to the first edge and / or second edge.

[0093] At least one section of the pleat(s) oriented along the common pleat direction may be a straight segment of the pleat(s), having one or all of the features disclosed above, particularly in the context of straight segments.

[0094] The folds of the paired folds and / or dense fold array(s) may extend through all atomic layers of the at least one top atomic layer, and the at least one top atomic layer may include at least three top atomic layers.

[0095] The graphite structure may further include at least two bulk atomic layers below the at least one top atomic layer with a bulk layer spacing between adjacent bulk atomic layers, and a pleated layer spacing between one atomic layer of the at least one top atomic layer and an adjacent layer of the at least one top atomic layer within the pleats. The pleated layer spacing may exceed the bulk layer spacing, particularly by at least 0.5%, particularly by at least 1% or at least 1.5%.

[0096] The change in atomic layer spacing at / within the folds can be considered as one of the origins of superconductivity arising from the folds, which may be the origin of the zero resistance state.

[0097] Bulk layer spacing may refer to the average spacing between adjacent bulk atomic layers of at least two bulk atomic layers.

[0098] For example, the bulk layer spacing may be 0.335 nm.

[0099] The fold spacing may be at least 0.336 nm, in particular at least 0.337 nm or 0.34 nm. Alternatively or additionally, the fold spacing may be at most 0.344 nm.

[0100] The at least two bulk atomic layers may be essentially flat.

[0101] In particular, the at least two bulk atomic layers may include corrugations that are significantly smaller than the corrugations of the at least one uppermost atomic layer.

[0102] The downward vertical extension of the pair of folds, or the majority of the dense fold array(s), or the majority of the folds of the plurality of folds, may terminate within at least one uppermost atomic layer.

[0103] A majority of the folds may refer to at least half of the folds.

[0104] The ratio of pleat height to pleat width of the twin pleats and / or dense pleat array may be at least 0.5, particularly at least 0.7, particularly at least 0.9, particularly at least 1.1 or at least 1.3.

[0105] A higher height to width ratio of the folds may contribute more to dissipation-free current and / or superconductivity.

[0106] The height of the fold(s) of the twin folds and / or dense fold array may be at most 10 nm, particularly at most 8 nm, in particular at most 6 nm, or at most 2 nm or at most 1 nm.

[0107] The average height of the folds of the twinned folds and / or dense fold array may be at most 10 nm, in particular at most 8 nm, in particular at most 6 nm, or at most 2 nm or at most 1 nm.

[0108] The pleat height of the twin pleats and / or dense pleat array may be at least 0.7 nm, particularly at least 1 nm, especially at least 2 nm or at least 3 nm.

[0109] The average height of the folds of the twinned folds and / or dense fold array may be at least 1 nm, in particular at least 2 nm or at least 3 nm.

[0110] The width of the folds of the twin folds and / or dense fold array may be at least 0.5 nm, in particular at least 1 nm or at least 1.5 nm.

[0111] The average width of the folds of the twinned folds and / or dense fold array may be at least 0.5 nm, in particular at least 1 nm or at least 1.5 nm.

[0112] The width of the folds of the twin folds and / or dense fold arrays may be up to 8 nm, in particular up to 6 nm or up to 5 nm.

[0113] The average width of the folds of the twinned folds and / or dense fold arrays may be at most 8 nm, in particular at most 6 nm or at most 5 nm.

[0114] The plurality of folds may include at least two pairs of folds, particularly at least three pairs of folds, particularly at least four pairs of folds, particularly at least five pairs of folds, particularly at least six pairs of folds, particularly at least seven pairs of folds, particularly at least eight pairs of folds, particularly at least nine pairs of folds, particularly at least ten pairs of folds, particularly at least 20 pairs of folds or at least 40 pairs of folds. Both the first electrode and the second electrode may be in electrical contact with both of the folds of each pair. Each distance between each fold of each pair may be up to 0.2 μm.

[0115] The fold pairs may be characterized by one or all of the features described above in the context of fold pairs.

[0116] Each distance may be characterized by one or all of the features described above in the context of the distance between pairs of folds.

[0117] The fractions of the pair of folds may include respective straight line segments.

[0118] Each straight line segment may extend along the direction of the respective straight line segment, and for a fraction of the pairs, or for a fraction of the pairs and / or folds of the dense fold array(s), the directions of the straight line segments may be parallel to each other.

[0119] For a fraction of the pair, the pair of folds can include parallel sections.

[0120] For a fraction of the pair, the paired plications may form a bifurcation or intersection.

[0121] A fraction of the folds of the pair(s) of folds and / or dense fold array(s) may extend along the first fold direction near and / or at their respective contacts to the first electrode.

[0122] A fraction of the folds of the pair(s) of folds and / or dense fold array(s) may extend along the second fold direction near and / or at their respective contacts to the second electrode.

[0123] Fraction may refer to at least 10%, particularly at least 20%, particularly at least 30%, particularly at least 40%, particularly at least 50%, particularly at least 60% or at least 80%.

[0124] Each fold of the pair(s) and / or dense fold array(s) may have a cross-sectional area, particularly in a plane perpendicular to the direction of the fold and / or the direction of a straight segment of the fold and / or to at least one uppermost atomic layer and / or surface.

[0125] The plurality of pleats may have a total cross-sectional area defined by the sum of the cross-sectional areas of all pleats in the pair(s) and / or dense pleat array(s).

[0126] The crease region has a temperature of at least 10 when the voltage between the first electrode and the second electrode is at most 10 nV and the temperature of the crease region is 295 K. 4 μA / cm 2The electrode may be adapted to support a current density between the first and second electrodes per total cross-sectional area of at least 10. In particular, the current density between the first and second electrodes per total cross-sectional area may be at least 10. 5 A / cm 2 , especially at least 10 7 A / cm 2 or 10 9 A / cm 2 may be.

[0127] The at least one top atomic layer may further include a second pleated region, the second pleated region being disposed or defined between two electrodes of the superconducting device associated with the respective pleated region. The second pleated region may include a second plurality of pleats having a second pair of pleats. Both electrodes may be in electrical contact with both pleats of the second pair of pleats. The distance between the pleats of the second pair may be up to 0.2 μm.

[0128] The second crease region may be characterized by one or all of the features described in the context of the crease region.

[0129] The second plurality of pleats may be characterized by one or all of the features described in the context of the plurality of pleats.

[0130] The second pair of plications may feature one or all of the features described in the context of the plication pair.

[0131] The at least one top atomic layer may include a plurality of crease regions, including the crease region and a second crease region, and each crease region of the plurality of crease regions may be characterized by one or all of the features described above in the context of the second crease region.

[0132] The two electrodes associated with each fold region may be a first electrode and a second electrode.

[0133] Alternatively or additionally, the superconducting device may include a third electrode disposed on the at least one uppermost atomic layer and spaced apart from the first and second electrodes, and the two electrodes associated with the second fold region may be the second and third electrodes.

[0134] The superconducting device may include a plurality of electrodes disposed on at least one top atomic layer. Any of the plurality of electrodes may be spaced apart from other electrodes of the plurality of electrodes. The plurality of electrodes may include a first electrode, a second electrode, and / or a third electrode.

[0135] The plurality of electrodes may comprise at least 4 electrodes, particularly at least 5 electrodes, particularly at least 6 electrodes, particularly at least 7 electrodes, particularly at least 9 electrodes, particularly at least 10 electrodes, particularly at least 50 electrodes or at least 100 electrodes.

[0136] Using multiple electrodes, the superconducting device may be expanded to span an extended area along one or two dimensions.

[0137] The superconducting device may be adapted to support a dissipation-free and / or superconducting current between two electrodes of the plurality of electrodes, particularly between any two electrodes of the plurality of electrodes, or between any pair of adjacent electrodes of the plurality of electrodes. For example, the superconducting device may be adapted to support a dissipation-free and / or superconducting current between two electrodes having a folded region associated with the two electrodes at room temperature.

[0138] Each fold region of the plurality of fold regions may be associated with a pair of electrodes of the plurality of electrodes, in particular a pair of adjacent electrodes.

[0139] The electrodes included in the plurality of electrodes may be interconnected by pleated regions, and in particular, adjacent electrodes of the plurality of electrodes may be interconnected by at least two pleated regions.

[0140] Any pair of adjacent electrodes of the plurality of electrodes may be interconnected by a pleated region, in particular by at least two pleated regions.

[0141] The electrodes included in the plurality of electrodes may be arranged essentially parallel to one another.

[0142] Each electrode may include at least one edge that defines a section of the boundary of the fold region, and in particular at least two edges that define the boundary of the fold region.

[0143] At least one edge (at least two edges) of at least two electrodes of the plurality of electrodes may be essentially parallel to each other.

[0144] In particular, at least one edge (at least two edges) of at least half of the electrodes of the plurality of electrodes may be essentially parallel to each other, or at least one edge (at least two edges) of all of the electrodes of the plurality of electrodes may be essentially parallel to each other.

[0145] Opposing edges of pairs of adjacent electrodes, in particular opposing edges of each of at least two pairs (or at least three pairs, or at least four pairs) of adjacent electrodes, may be parallel to one another.

[0146] The superconducting device may further include a third electrode disposed on the at least one top atomic layer and spaced apart from the first and second electrodes. The at least one top atomic layer may include a second folded region defined between the second and third electrodes. The second folded region may include a second plurality of folds. The second and third electrodes may be in electrical contact with each fold of the second plurality of folds. For each fold of the second plurality of folds, the distance between each fold and an adjacent fold may be up to 0.2 μm.

[0147] The superconducting device may further comprise a plurality of electrodes, including a first electrode and a second electrode, wherein the plurality of electrodes comprises at least four electrodes spaced apart from one another. The superconducting device may further comprise a plurality of folded regions of at least one top atomic layer, wherein the plurality of folded regions comprises at least three folded regions. A folded region included in the plurality of folded regions may be associated with a respective pair of electrodes of the plurality of electrodes, may be disposed between each associated pair of electrodes, and may comprise a respective plurality of folds comprising each pair of folds. Each associated pair of electrodes may be in electrical contact with both folds of each pair. The distance between the folds of each pair may be up to 0.2 μm. Any two electrodes of the plurality of electrodes may be electrically interconnected via the folded regions and / or electrodes. In such embodiments, the plurality of electrodes may comprise at least five electrodes, particularly at least six electrodes, particularly at least eight electrodes, particularly at least 10 electrodes, particularly at least 20 electrodes, particularly at least 50 electrodes, or at least 100 electrodes. Alternatively or additionally, in such embodiments, the plurality of pleat regions may comprise at least 5 pleat regions, particularly at least 6 pleat regions, particularly at least 8 pleat regions, particularly at least 10 pleat regions, particularly at least 20 pleat regions, particularly at least 50 pleat regions or at least 100 pleat regions.

[0148] The superconducting device has a maximum capacitance of at least 10 per total cross-sectional area of the fold when an external field of 9 T is applied to the fold region. 6 A / cm 2 may be further adapted to provide a current between the first electrode and the second electrode.

[0149] The superconducting device has a maximum capacitance of at least 10 per total cross-sectional area of the fold when an external field of 9 T is applied to the fold region. 7 A / cm 2 Or at least 10 8 A / cm 2 may be adapted to provide a current between the first electrode and the second electrode.

[0150] A second aspect relates to the use of a pleated region of at least one top atomic layer of a graphite structure for a superconducting device, wherein the pleated region comprises a plurality of pleats including a pair of pleats, and the distance between the pair of pleats is at most 0.2 μm.

[0151] A superconducting device may be characterized by one or all of the above features.

[0152] The superconducting device may be a device in which a superconducting and / or essentially dissipative electrical current flows through the pleated region and the temperature of the pleated region is in the range of 280K to 310K.

[0153] The use may further include driving a superconducting and / or essentially dissipative current through the folded region, in particular, a current density in the folded region of at least 10 at a temperature in the folded region not exceeding 4.5 K. 9 A / cm 2 and in particular, at least 10 8 A / cm 2 is.

[0154] The superconducting device can include a crossover magnetic field, which can correspond to a magnetic field in the pleated region, particularly perpendicular to a surface defined by the at least one top atomic layer and / or at least one flat section of the at least one top atomic layer, wherein the resistivity of the pleated region or the room temperature superconducting device is independent of the temperature of the pleated region.

[0155] For example, the crossover field may be 0.01T, or 0.02T, or 0.03T, or 0.035T.

[0156] The use may further comprise applying a magnetic field in the crease region, in particular a magnetic field perpendicular to the surface defined by the at least one top atomic layer and / or at least one flat section of the at least one top atomic layer.

[0157] The applied magnetic field may exceed the crossover field.

[0158] The method can further include, during application of the magnetic field in the folded region, subjecting the folded region to a temperature above the reference temperature to increase a critical current in the folded region compared to a critical current in the folded region at the reference temperature, the reference temperature being in the range of 4.5 K to 100 K.

[0159] The superconducting device may further comprise a third electrode and a fourth electrode, and using may include driving a current through the folded region through the third electrode and the fourth electrode.

[0160] The superconducting device, the graphite structure, the at least one top atomic layer of graphite, the plurality of folds, the first electrode, the second electrode, the third electrode, the fourth electrode, the surface, and the current may be characterized by one or all of the features described above.

[0161] In a third aspect, a method for fabricating a superconducting device includes providing a pleated region in at least one top atomic layer of a graphite structure, the pleated region including a plurality of pleats having pairs of pleats, the distance between the pairs of pleats being at most 0.2 μm. The method further includes disposing a first electrode on the at least one top atomic layer in electrical contact with the pairs of pleats, and disposing a second electrode on the at least one top atomic layer in electrical contact with the pairs of pleats, such that the second electrode is displaced from the first electrode along the at least one top atomic layer and the pleated region is located between the first electrode and the second electrode.

[0162] The pleated region may be adapted to support a current between the first and second electrodes of at least 5 μA / mm per width of the pleated region when the voltage between the first and second electrodes is at most 10 nV and the pleated region is at room temperature.

[0163] Providing the pleated region may further include providing a graphite base material and fracturing the graphite base material.

[0164] Breaking the graphite-based material may include mechanically peeling off a portion of the graphite-based material. In particular, breaking the graphite-based material may include attaching a breaking element to the graphite-based material and mechanically removing the breaking element and a portion of the graphite-based material. Attaching the breaking element to the graphite-based material may include applying an adhesive to the graphite-based material. The adhesive may be adapted to mechanically bond the breaking element to the graphite starting material upon attachment of the breaking element.

[0165] Fracturing the graphite-based material may include fracturing the graphite-based material essentially between a first atomic layer of the graphite-based material and a second atomic layer of the graphite-based material.

[0166] Fracturing the graphite-based material may involve removing at least one, in particular at least 10 or at least 100 atomic layers from the graphite-based material.

[0167] Fracturing the graphite-based material can include producing a surface of the graphite structure corresponding to an atomic layer of graphite. Alternatively or additionally, the surface can be defined by at least one uppermost atomic layer.

[0168] Fracturing the graphite-based material can include producing an as-fractured pleat region having a plurality of as-fractured pleats, particularly parallel as-fractured pleats.

[0169] The method can further include selecting a fold region from the as-fractured fold region. For example, the method can include selecting a fold of the fold region from the as-fractured folds of the as-fractured fold region.

[0170] The method can further include positioning a first electrode according to a selection of a fold region from the as-fractured fold region and positioning a second electrode according to the fold region. For example, the method can include positioning the first electrode and positioning the second electrode to contact as-fractured folds of the as-fractured fold region with the first electrode and the second electrode, thereby generating folds of the fold region in electrical contact with the first electrode and the second electrode.

[0171] Disposing the first electrode on the at least one top atomic layer and / or disposing the second electrode on the at least one top atomic layer can include masking the at least one top atomic layer.

[0172] Disposing a first electrode on the at least one top atomic layer and / or disposing a second electrode on the at least one top atomic layer can include depositing a conductive material on the at least one top atomic layer, particularly after masking. The conductive material can include a noble metal such as gold, silver, or copper.

[0173] The method may further include disposing a third electrode on the at least one top atomic layer.

[0174] The method can further include defining a second folded region of the top atomic layer using two electrodes.

[0175] A superconducting device may be characterized by one or all of the above features. [Brief explanation of the drawings]

[0176] The techniques of the present disclosure and their associated advantages will become most apparent from a description of exemplary embodiments taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 illustrates a superconducting device according to one embodiment. [Figure 2] FIG. 1 illustrates the pleats of a superconducting device. [Figure 3a]FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 3b] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 3c] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 3d] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 3e] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 4a] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 4b] FIG. 1 illustrates a superconducting device according to another embodiment. [Figure 5a] FIG. 1 is a diagram showing the current-voltage characteristics of a superconducting device. [Figure 5b] FIG. 10 illustrates another current-voltage characteristic of a superconducting device. [Figure 6a] FIG. 1 shows the magnetization curve of a superconducting device. [Figure 6b] FIG. 2 is a diagram showing the magnetization curve of a conventional superconductor for reference. [Figure 6c] FIG. 1 shows the temperature dependence of the critical current of a superconducting device. [Figure 7] FIG. 1 illustrates the magnetic field dependence of the critical current of a superconducting device. [Figure 8a] FIG. 1 illustrates a method for fracturing a graphite-based material. [Figure 8b] FIG. 10 shows the top graphite layer after cleaving. [Figure 9a] FIG. 10 is a schematic diagram of pleat formation during fracturing. [Figure 9b] FIG. 10 is another schematic diagram of pleating during fracturing. [Figure 9c] FIG. 10 is another schematic diagram of pleating during fracturing. [Figure 10a] 1A-1C are schematic diagrams of process steps for providing a pleated region. [Figure 10b] 10A-10C are schematic diagrams of alternative process steps for providing a pleated region. [Figure 10c] 10A-10C are schematic diagrams of alternative process steps for providing a pleated region. DETAILED DESCRIPTION OF THE INVENTION

[0177] 1 is a schematic diagram of a superconducting device according to a first embodiment. The device comprises a graphite structure 100, more particularly its top layer 102 along the vertical direction z (pointing into the plane of the figure).

[0178] The top layer 102 comprises folds 114 that are line defects in the (regular) planar arrangement of carbon atoms in the top layer 102. More specifically, the carbon atoms in the folds 114 are offset from the x,y plane corresponding to the planar section of the top layer 102 having the (regular) planar arrangement of carbon atoms therein. In other words, the folds 114 protrude along the (negative) vertical direction (-)z from the x,y plane defined by the planar section of the top layer 102.

[0179] The folds 114a, 114b, and 114c are close enough to each other to allow electronic coupling between them, which is beneficial for establishing room-temperature superconductivity. In other words, the spacing or distance between the folds 114 is below a critical value for sufficient electronic coupling. Our experiments indicate that this critical value is in the range of 2 to 200 nm, and possibly in the range of 2 to 100 nm.

[0180] Various techniques can be applied to characterize the distance between the folds 114a, 114b, 114c.

[0181] One related approach is to use a minimum distance d1 between the fold pairs 114a, 114b; 114b, 114c. The section of the folds 114a, 114b, 114c that defines the minimum distance contributes significantly to electronic coupling and therefore superconductivity.

[0182] Another related approach is to calculate the average distance between each pair of adjacent folds 114a, 114b.

number

number

number

number

[0183] The plurality 114 of pleats 114a, 114b, 114c are located within a (pleated) region 112 of the top layer 102. The outermost pleats 114a, 114c of the plurality of pleats 114 form the boundary of the pleated region 112.

[0184] Electrodes 110, 120 are disposed on the top layer 102 and electrically contact the folds 114 at different locations corresponding to the edges 110e, 120e of the electrodes.

[0185] The electrodes 110 , 120 or their respective edges 110 e , 120 e that contact the fold 114 can be considered to form the boundary of the fold region 112 .

[0186] As will be explained in more detail throughout this disclosure, the structures implement high temperature superconductors, or room temperature superconductors, which have critical temperatures above room temperature even at ambient pressure.

[0187] Figure 2 provides a detailed view to schematically illustrate a possible structure of the folds 114. This view can be considered as a cross section through one of the folds 114a, 114b, 114c of the fold region 112 of Figure 1 parallel to the y,z plane.

[0188] Graphite has a layered structure of (carbon) atoms in which layers characterized by interatomic distances of less than 0.2 nm are separated from each other by layer spacings 206, 216 of less than 0.3 nm.

[0189] 2, the folds 114 extend through the three top atomic layers 102a, 102b, 102c of graphite. In alternative embodiments, the folds 114 may extend through two, four, five, six, or more top atomic layers 114.

[0190] The bulk atomic layers 214 below the top atomic layer 114 are essentially flat and unaltered by the folds 114. According to this example, three bulk atomic layers 214 are shown, 10, 10 2 ,10 3 ,10 4 ,10 5 ,10 6 ,10 7 There may be more bulk atomic layers 214, such as 100 or more.

[0191] The folds 114 bend away from the surface with radii R1, R2 in the nanometer range, for example, 1-100 nm, and correspondingly, the bending radius r at the top of the folds 114 is in a similar range.

[0192] As a result, the height 202 and width 204, which can be used for alternative characterization (compared to the radii R1, R2, r), are also in the nanometer range.

[0193] The radii R1, R2, r (or height 202 and width 204, respectively) in the nanometer range result in a change in the atomic arrangement at and / or within the folds 114 compared to the regular arrangement of (carbon) atoms in graphite, e.g., in a flat section of the top atomic layer 102 or in the bulk atomic layer 214.

[0194] For example, the interlayer spacing 206 within and / or at the folds 114 is 0.336 to 0.344 nm, which is larger than the atomic layer spacing 216 (0.335 nm) of the bulk atomic layer 214 .

[0195] Furthermore, the stacking order of the (top) atomic layers 102a, 102b, 102c varies at and / or within the folds 114. This is illustrated in Figure 2 by depicting a section 210 outside the folds 114 and atoms 208 within a section 212 of the folds 114.

[0196] 2, in the section 210 outside the folds 114, the atoms of the first and third top atomic layers 102a and 102c are arranged directly on top of each other (along the plane x, y). This type of stack is called a vernal.

[0197] In contrast, in section 212 of fold 114, atoms in first top atomic layer 102a, second top atomic layer 102b, and third top atomic layer 102c are each displaced relative to one another. This type of stacking differs from the stacking in section 210 outside the fold as a function of bending radius R1. The change in stacking affects the electronic structure and can induce superconductivity.

[0198] 2, atoms of the fourth and top atomic layer (if present with a fold below the third and top atomic layer 102c) can be arranged directly (along the x,y plane) below atoms of the first and top atomic layer 102a. Such an arrangement is called a rhombohedron and is commonly realized in graphite.

[0199] Changes in atomic arrangement at and / or within the folds 114, compared to the regular arrangement of (carbon) atoms in graphite, can result in local modifications of the graphite's electronic structure and local superconductivity. As shown in Figure 1, the extended geometry of the folds 114 and the coupling of folds within the fold region 112 perpendicular to the folds 114 transform and transition this local superconductivity to superconductivity characterized by a zero-resistance state that supports dissipationless current transport through the fold region 112 or between the electrodes 110, 120.

[0200] Figures 3a, 3b, 3c, 3d, and 3e show variations of the superconducting device of Figure 1. In the context of these figures, various variations are described. According to different embodiments, one, all, or any combination of the variations described may be implemented.

[0201] The embodiment of Figure 3a is similar to that of Figure 1. However, pairs 114a, 114b; 114c, 114d of pleats 114 in the embodiment of Figure 3a include parallel sections 116a, 116b; 116b, 116c. These parallel sections beneficially contribute to and increase the electronic coupling between pleats 114 and, therefore, the critical temperature of the superconducting device.

[0202] The distance d2 between the parallel sections 116a, 116b, 116c can serve as a measure of the distance between the pleats 114.

[0203] According to an embodiment, the parallel sections 116a, 116b; 116b, 116c coincide with the sections of minimum distance between the pleats 114a, 114b; 114b, 114c. This arrangement is not required, but is beneficial for strengthening the bond between the pleats 114a, 114b, 114c.

[0204] According to an embodiment, the pleats 114 have straight segments 116a, 116b, 116c that coincide (at least partially) with parallel sections 116a, 116b, 116c. While this arrangement is not required, it is beneficial to strengthen the bond between the pleats 114a, 114b, 114c.

[0205] According to this embodiment, each pleat pair 114a, 114b; 114b, 114c includes a respective parallel section 116a, 116b; 116b, 116c. While this arrangement is not required, it is beneficial for strengthening the bond between pleats 114a, 114b, 114c. According to an alternative embodiment, only some of the pleats 114 include parallel sections.

[0206] The embodiment of Figure 3b is similar to that of Figure 1. However, the fold pair 114a, 114b in Figure 3b exhibits a crossover (intersection) 126, and the fold pair 114b, 114c exhibits a bifurcation 128.

[0207] The intersections 126 and bifurcations 128 are characterized by zero distance between the folds 114a, 114b.

[0208] At the intersection (crossing portion) 126, the number of pleats 114 in the reference planes 126a, 126b is the same. The reference planes 126a, 126b are perpendicular to the direction x in which the pleats 114 extend, and are located at different positions along the direction x before and after the intersection (crossing portion) 126.

[0209] At the bifurcation 128, the reference surfaces 128a and 128b have different numbers of folds 114. The reference surfaces 128a and 128b are perpendicular to the direction x in which the folds 114 extend, and are located at different positions along the direction x before and after the bifurcation 128.

[0210] The branches 128 and / or intersections 126 further strengthen the coupling between the pleats 114 and support the formation of a current path for dissipationless supercurrent through the pleat region 112 .

[0211] The embodiment of Figure 3c is similar to that of Figure 1. However, the folds 114a, 114b, and 114c in Figure 3c exhibit a first fold direction 118a near the electrode 110 that is perpendicular to (the edge 110e of) the electrode 110. Furthermore, the folds 114b and 114c near the second electrode 120 exhibit a second fold direction 118b that is perpendicular to (the edge 120e of) the second electrode 120. In other words, the electrodes 110 and 120 contact the folds 114b and 114c at an essentially 90° angle (perpendicular). The fold 114a electrically contacts the first electrode 110 at an angle (perpendicular).

[0212] Contacting the pleats 114 with the electrodes 110, 120 at a 90° angle has been found to be beneficial in using the electrodes 110, 120 to drive significant dissipationless (superconducting) current through the pleat region 112. In other words, the perpendicular contact improves the critical current of the superconducting device.

[0213] According to the embodiment of Figure 3c, each of the pleats 114a, 114b, 114c of the plurality of pleats 114 has the same first pleat direction 118a near the electrode 110 or at the contact with the edge 110e. However, beneficial effects may still be obtained if only a portion (e.g., a quarter, a third, or a half) of the pleats 114 have the first pleat direction 118a. The same is true for the second pleat direction 118b near the second electrode 120. According to the example of Figure 3c, the pleats 114b, 114c have the second pleat direction 118b.

[0214] The embodiment of Figure 3d is similar to that of Figures 1 and 3c, however the electrodes 110, 120 are shaped to ensure that the electrodes 110, 120 are perpendicular to the first fold direction 118a and the second fold direction 118b.

[0215] The embodiment of Figure 3e is similar to the embodiments of Figures 1, 3a, 3c, and 3d. This embodiment combines some of the beneficial features described above in the context of those embodiments. The pleats 114 of Figure 3e each have linear parallel segments 116a, 116b, 116c, and 116d (see Figure 3a). The pleats 114 each have a first (second) pleat direction 118a (118b) near the first (second) electrode 110 (120), and the angle between the first (second) pleat direction 118a (118b) and the first (second) electrode 110 (120) is 90°.

[0216] Each of the folds 114d has an adjacent fold on its first side (toward the positive y direction in FIG. 3e) and an opposite adjacent fold on its opposite side (toward the negative y direction in FIG. 3e), each with a spacing or distance below a critical value for sufficient electronic coupling. In the context of this disclosure, corresponding folds 114d are referred to as densely packed folds 114d or dense fold arrays 114d. They, in combination with electrodes 110, 120, if present, define dense fold regions 112d. In contrast to fold region 112, which may include sections without folds 114, dense fold regions 112d are completely filled with dense fold arrays 114d.

[0217] The dense pleat array of Figure 3e consists of two pleats 114d, but may include more pleats or a single pleat, such as pleat 114b of Figures 1, 3a, 3b, 3c and 3d.

[0218] Figures 4a and 4b show modifications of the superconducting devices of Figures 1, 3a, 3b, 3c, 3c, 3d, and 3e. Various modifications are described in the context of these figures. According to different embodiments, one, all, or any combination of the described modifications may be implemented.

[0219] The embodiment depicted in Figures 4a and 4b includes multiple electrodes 110, 120, 130, 140, 150, 160, and 170. Fold regions 112, 122, 132, 142, 152, and 162 are located between each pair of electrodes 110, 120, 130, 140, 150, 160, and 170, or between corresponding edges 150e and 160e of electrodes 150 and 160, respectively (only some of the edges are indicated by reference numerals, but corresponding edges exist for all electrodes 110, 120, 130, 140, 150, 160, and 170, typically on both sides of electrodes 120, 130, 140, 150, and 160).

[0220] Each of the fold regions 112, 122, 132, 142, 152, and 162 includes multiple densely fold regions 112d, 122d, 132d, 142d, 152d, and 162d. The fold regions 112d, 122d, 132d, 142d, 152d, and 162d, shown with dashed lines, are contiguous. In other words, they do not include any flat sections with widths exceeding a critical width.

[0221] The superconducting device of Figures 4a and 4b further comprises conductive wires 110w, 170w to current source 300. Wires 110w, 170w abut electrodes 110, 170 at contacts 110c, 170c, thus connecting electrodes 110, 170 to current source 300. Current source 300 provides a current J below the critical current of the superconducting device, which transports current J between electrodes 110, 170 through folded regions 112, 122, 132, 142, 152, and 162. While wires 110w, 170w and contacts 110c, 170c to electrodes 110, 170 are shown in accordance with the embodiment shown in Figures 4a and 4b, electrodes 120, 130, 140, 150, and 160 may alternatively or additionally be provided with wires and contacts (not shown) to current source 300.

[0222] Corresponding embodiments allow the superconducting device to be scaled to extended lengths along one or two dimensions.

[0223] The embodiment depicted in FIG. 4a further includes isolated folds 114′, i.e., folds 114′ that do not have any neighboring folds within a critical spacing or distance required for sufficient electronic coupling. In other words, the folds 114′ are not part of a pair or dense fold array. The isolated folds 114′ do not contribute to the superconductivity or supercurrent of the superconducting device. However, the presence of the isolated folds 114′ does not interfere with superconductivity, and isolated folds 114′ may be present within the fold region 112.

[0224] In contrast, dense-fold regions 112d, 122d, 132d, 142d, 152d, and 162d do not contain any isolated folds. As explained above in the context of FIG. 3e, each dense-fold region 112d, 122d, 132d, 142d, 152d, and 162d is completely filled with dense-fold arrays 114d, maximizing the critical current density of superconducting (dissipationless) current in these regions 112d, 122d, 132d, 142d, 152d, and 162d.

[0225] Figures 5a and 5b show the measured current-voltage characteristics for different magnetic fields B and the device layouts corresponding to one of Figures 4a and 4b. To establish the device, eleven electrodes 110, 120, 130, 140, 150, 160, and 170 of silver-doped conductive epoxy were deposited on appropriate sections (folded regions 112, 122, 132, 142, 152, and 162) of the surface of fractured highly oriented pyrolytic graphite. The distance between adjacent electrode pairs 110, 120; 120, 130; 130, 140; 140, 150; 150, 160; and 160, 170 along the x-direction (the width of the folded regions 112, 122, 132, 142, 152, and 162) was 0.2 mm.

[0226] For each measurement, the current I (A), I (mA) driven through the device with current source 300 is shown on the bottom axis, and the voltage drop V (μA) measured between pairs of electrodes 110, 120, 130, 140, 150, 160, 170 is shown on the left axis. Figure 5a shows the current-voltage characteristics B0, B2, B5, B9 on a semi-logarithmic scale for magnetic fields of 0 T, 2 T, 5 T, and 9 T. Figure 5b shows the current-voltage characteristics on a linear scale for a magnetic field of 0.2 T. All measurements were performed with the superconducting device at a temperature of 300 K.

[0227] All measurements shown in Figures 5a and 5b demonstrate that for sufficiently small currents driven through the device, the voltage drop V (μA) is zero, i.e., below the resolution limit of the measurement equipment (10 nA). As a result, the resistance R, R = V / I, of the superconducting device, defined by the voltage drop V (μA) per current I (A), I (mA) driven through the device, is zero within the resolution limit of the measurements. This is the case for currents I (A), I (mA) between electrodes 110 and 170 that are below the critical current I (A), I (mA) of the superconducting device (e.g., approximately 0.08 mA in Figure 5b). At the critical current I, the voltage drop V (μA) shows a sharp increase toward higher currents I (A), I (mA). In other words, the voltage drop V (μA) increases suddenly and significantly, resulting in a much larger resistance R = V / I that is easily detectable with the applied measurement equipment. For example, in Figure 5b, for a current I (mA) of 0.3 mA (greater than Ic), the voltage drop will be about 0.6µA, and the resistance R = 0.6µA / 0.3mA.

[0228] The disappearance of the measured resistance (within the resolution limits of the measurement) of the superconducting device provides direct evidence of dissipation-free current transport (within the resolution limits of the measurement) through the superconducting device, i.e., between the electrodes 110, 120, 130, 140, 150, 160, 170 and / or through the pleated regions 112, 122, 132, 142, 152, 162. In general, the dissipated power P is given by P=RI 2 Therefore, it is related to the current I (A) and I (mA). When the resistance R is zero, the dissipated power is zero and the current I (A) and I (mA) are dissipated.

[0229] Figure 6a shows the magnetization curve 606 of a superconducting device according to the present disclosure, and Figure 6b shows the corresponding reference measurement 608 of conventional superconductor Bi2Sr2CaCu2O8 at a temperature (60 K) below its critical temperature (90 K). The magnetizations M (G) and M (mG) of each material were then measured while applying external magnetic fields H and H (Oe).

[0230] 6a, during measurements, a magnetic field H was applied either perpendicular to the top atomic layer 102 or along the c-axis c of the flat section of the top atomic layer 102 (which coincides with the c-axis of the bulk atomic layer 214, if present), respectively. For the measurements, the superconducting device was kept at a temperature of 300 K. The magnetization of the superconducting device was measured as the magnetic field H increased (as indicated by the arrow 602 to the right) and as the magnetic field H decreased (as indicated by the arrow 604 to the left). The measured magnetization curve 606 is hysteretic, i.e., its shape is significantly different depending on whether the magnetic field H is increasing 602 or decreasing 604.

[0231] The magnetization curve 606 of Figure 6a is very similar to the reference magnetization curve 608 measured on the conventional, well-established superconductor Bi2Sr2CaCu2O8 (below its critical temperature) shown in Figure 6b. The similarity provides direct experimental evidence that the graphite structure 100 not only functions as a superconducting device in the sense that it supports dissipationless current, but also radiates an external magnetic field (exhibiting the Meissner effect) just as the conventional superconductor Bi2Sr2CaCu2O8 of the reference measurement 608 does.

[0232] We decided to perform a reference measurement on BiSrCaCuO because, like graphite, BiSrCaCuO has a layered crystal structure. For measurement 608 in Figure 6b, a magnetic field H was applied perpendicular to the atomic layers of BiSrCaCuO, or along its c-axis.

[0233] FIG. 6c summarizes the critical current Ic (mA) determined from multiple measurements similar to those in FIGS. 5a and 5b for various temperatures T and magnetic fields B.

[0234] For each temperature T (e.g., T=4.5K, T=20K, T=100K, ...), the critical current Ic (mA) decreases with increasing magnetic field B(T), as is typically observed for superconductors.

[0235] When observing the critical current Ic (mA) at a given magnetic field B(T) above the critical magnetic field Bcr (i.e., along the vertical line in Figure 6c), the critical current Ic (mA) increases with temperature. For the example in Figure 6c, the critical magnetic field Bcr is 35 mT. This behavior is, to the best of our knowledge, unique and specific, since the critical current Ic (mA) of conventional superconductors decreases with increasing temperature (as observed for the superconducting device in Figure 6c for magnetic fields B(T) below the critical magnetic field Bcr).

[0236] The unique behavior shown in Figure 6c makes superconducting devices according to the present invention particularly attractive for applications in environments where a magnetic field is present. By operating the superconducting device at a sufficiently high temperature, the reduction in critical current Ic (mA) caused by the magnetic field B (T) can be compensated for. For example, a magnetic field is not intended and could otherwise be avoided only at the expense of considerable engineering effort and corresponding costs. In other applications, a magnetic field may be required for functions other than superconductivity (e.g., for an electric motor).

[0237] Figure 7 compares the temperature dependence of the critical current Ic (A) for a magnetic field B0' (0 T) below the critical field Bc and a magnetic field B1 (1 T) above the critical field Bc. As mentioned above, the former decreases with increasing temperature T (K), exhibiting conventional behavior, while the latter increases with temperature T (K), reflecting the unique properties of the superconducting device according to the present invention.

[0238] Additionally, FIG. 7 illustrates the inverse bulk non-superconducting state resistance R of graphite using solid lines 700a, 700b. N In other words, the solid lines 700a and 700b represent the function Ic=c / R N, where c is a constant (0.19 μV in the example of FIG. 7). On the other hand, the solid line 700a represents the bulk non-superconducting state resistance R N , using the function Ic=c / R N 700b shows the function for a magnetic field of 1 T.

[0239] On the other hand, the functions 700a and 700b shown in the figure, Ic=c / R N are in good agreement with the measured critical currents Ic, B0', and B1. On the other hand, the functions 700a, 700b, Ic=c / R N The only physical quantity that is relevant is the bulk non-superconducting state resistivity R of graphite. N Combined, these two observations provide clear evidence that the superconductivity of the superconducting device, as characterized by the critical current Ic, is mediated by the (normal) bulk graphite. In other words, the (normal) bulk graphite underlying the pleated top layer 102 contributes beneficially to superconductivity.

[0240] FIG. 8a shows a method 708 for producing a surface 706 of a graphite-based material 704 having a top atomic layer 102, and FIG. 8b shows the resulting surface 706.

[0241] Referring to FIG. 8a, first, a suitable graphite base material 704 is provided.

[0242] Our experiments have shown that a high degree of parallelism between adjacent atomic layers 214 of bulk graphite and / or graphite-based material 704, respectively, is beneficial for superconductivity. The parallelism can be characterized by the distribution of c-axes of the bulk atomic layers 214. The c-axis of each atomic layer refers to the axis perpendicular to the atomic layer. The c-axes should be aligned within 2°, preferably within 0.5° or 0.2°.

[0243] Moreover, our experiments indicate that a graphite-based material 704 having a high resistivity perpendicular to its atomic planes 214 (compared to the resistivity along its atomic planes 214) is beneficial for superconductivity. Ideally, the resistivity perpendicular to the layers 214 is at least 100,000 times greater than the resistivity parallel to the atomic layers 214.

[0244] Highly oriented pyrolytic graphite has been found to be suitable for the graphite base material 704 .

[0245] Still referring to FIG. 8a, an adhesive tape 702 is applied to the top side of the graphite base material 704.

[0246] The adhesive tape 702 is then pulled away from the graphite-based material 704 along a direction 700 that is essentially parallel to the top side of the graphite-based material 704. The adhesion between the adhesive tape 702 and the top layer of the graphite-based material 704 is stronger than the adhesion between the top layer of the graphite-based material 704 and the atomic layers of graphite below it. As a result, pulling the graphite-based material 704 away along the direction 700 removes the top layer attached to the adhesive tape 702 from the graphite-based material 704, opening the top atomic layers 102 of the surface 706 thus created. This process is referred to as fracturing 708. The bulk atomic layers 214 remain unchanged by the fracturing 708.

[0247] 8b is a schematic illustration of a surface 706 created by fracturing 708 and defined by the top atomic layer 102. Folds 114 perpendicular to the fracturing direction 700 are found on the surface 706 after fracturing 708. At least in part, the folds 114 exhibit parallel sections 116.

[0248] In a next step, crease regions 112a, 112b on surface 706 are selected to exhibit the characteristics described above in connection with Figures 1, 3a, 3b, 3c, 3d, and 3e. The sections 112a, 112b shown in Figure 8b provide an exemplary possible selection of such crease regions 112a, 112b.

[0249] In a next step, electrodes are deposited onto / onto the surface 706 according to the selected fold regions 112a, 112b. In particular, the electrodes are deposited such that their edges coincide with the boundaries 710, 712 of the selected fold regions 112a, 112b that are perpendicular to the folds 114 (and parallel to the fracturing direction 700).

[0250] Therefore, a mask is provided to shield the crease regions 112a, 112b during electrode deposition.

[0251] A mask is then used to shield the crease regions 112 a, 112 b and a conductive material is deposited on the surface 706 to complete the superconducting device. For example, the conductive material may be deposited using molecular beam epitaxy or chemical vapor deposition, applying techniques known in the context of silicon semiconductor technology, or the conductive material may be deposited from a liquid phase, for example in the form of a silver-doped conductive epoxy.

[0252] 9a, 9b, and 9c show the creation of pleats 114 during the fracturing 708 process.

[0253] 9a illustrates schematically the initial stages of removing adhesive tape 702 from graphite-based material 704 along direction 700 to create surface 706, as described above in connection with FIG. 8a. Pulling adhesive tape 702 along direction 700 creates a force along direction 700 on the adhesive tape 702 and the atomic layers of graphite-based material 704 near surface 706.

[0254] 9b shows a schematic diagram of a subsequent stage after removal of the adhesive tape 702. The force along the direction 700 results in a partial shift of the top atomic layer 102 along the direction 700, resulting in folds 114 in the top atomic layer 102 near the generated surface 706. The bulk atomic layer 214 below the top atomic layer 102 and sufficiently far from the surface 706 (separated from the surface 706 by the top atomic layer 102) remains unchanged by the folds 114.

[0255] 9c shows schematically the final stage of removal of adhesive tape 702, i.e., the adhesive tape has been completely removed from surface 706. The formation of folds 114 of the top atomic layer 102 perpendicular to direction 700 is completed.

[0256] 10a, 10b and 10c show an alternative method of producing the pleats 114 and the top atomic layer of graphite, preferably in a parallel arrangement of pleats 114. FIG.

[0257] Figure 10a shows a top view of the fracturing cut 708, which was described in detail above in the context of Figures 8a, 9a, 9b, and 9c. Because the folds 114 produced by the fracturing cut 708 are each essentially perpendicular to the fracturing direction 700, they exhibit long parallel segments 116. These are formed in the fracturing process 708 essentially parallel to the interface separating the graphite base material 704 with the adhesive tape 702 thereon from the surface 706 of the graphite base material 704 produced in the fracturing process 708.

[0258] 10b shows the formation 800 of folds 114 in the top layer 102 using an acoustic or light source 802 emitting acoustic or light waves 804. The acoustic or light waves 804 interact with an (initially flat) graphite surface to generate the folds 114. Details of a corresponding technique using acoustic waves are described in A.V.A. Laferdov, et al., “Ripplocation in graphite nanoplatelets during sonication-assisted liquid phase exfoliation,” Carbon 129, 826-829 (2018). Details of a corresponding technique using light waves are described in T. Zou et al., “High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse,” Light: Science & Applications volume 9, 69 (2020).

[0259] 10c shows the formation 810 of folds 114 in the top layer 102 using a nano- or micro-probe 812. The nano- or micro-probe 812 interacts with the (initially flat) graphite surface, generating a force parallel to the x,y surface plane of the top atomic layer 102. This force ultimately results in folds 114 in the top atomic layer 102. Details are described, for example, in B. Jayasena et al., “A novel mechanical cleavage method for synthesizing few-layer graphenes,” Nanoscale Research Letters 6, 95 (2011) or in X. Lu et al., “Tailoring graphite with the goal of achieving single sheets,” Nanotechnology 10, 269 (1999).

[0260] The description of the embodiments and drawings only serves to illustrate the techniques of the present disclosure and the associated advantageous effects, and should not be understood to mean any limitation. The scope of the present disclosure is determined by the appended claims. [Explanation of symbols]

[0261] 100 Graphite Structure 102, 102a, 102b, 102c at least one top atomic layer 110 first electrode 110c contact 110e Edge of first electrode 110w First electrode wiring 112, 122, 132, 142, 152, 162 Fold area 112d, 122d, 132d, 142d, 152d, 162d High-density fold array 114 Multiple Pleats 114a, 114b, 114c folds 114d. Closely packed folds, folds with each adjacent fold and opposite adjacent fold. 114' Isolated Fold 116a, 116b, 116c parallel compartments 118a: First fold direction perpendicular to the first electrode 118b: a second fold direction perpendicular to the second electrode 120 Second electrode 120e Edge of second electrode 126 Intersection 126a First reference plane of intersection 126b Second reference plane of intersection 128 Intersection 128a First reference plane of intersection 128b Second reference plane of intersection 130, 140, 150, 160, 170 electrodes 150e, 160e Edges of the fifth electrode and sixth electrode 170c contact 170w electrode wiring 300 current source B0, B2, B5, B9 Voltage-current characteristics for different magnetic fields B0', B1 Temperature dependence of critical current in the absence and presence of a magnetic field Bcr critical magnetic field 602 Magnetic Field Increase 604 Magnetic field decrease 606 Magnetization curves of superconducting devices 608 Reference Magnetization Curve, Conventional Superconductor 700a, 700b Solid lines: bulk non-superconducting state resistance R N Functions of 700 Cutting direction 702 Adhesive tape 704 Graphite Base Material 706 Surface 708 Cutting 112a, 112b Folded surface area 710 Edge of a pleated surface area 712 Edge of a pleated surface area Generate folds using 800 wave (light wave, sound wave) sources 802 Wave (light wave, sound wave) source 804 Waves (light waves, sound waves) 810 Creating folds with a scanning probe 812 Scanning Probe

Claims

1. 1. A superconducting device, comprising: a graphite structure (100) having at least one top atomic layer (102); a first electrode (110) disposed on the at least one uppermost atomic layer (102); a second electrode (120) disposed on the at least one uppermost atomic layer (102) and spaced apart from the first electrode (110); a pleated region (112) of the at least one uppermost atomic layer (102), the pleated region (112) being disposed between the first electrode (110) and the second electrode (120), the pleated region (112) including a plurality of pleats including pairs of pleats (114a, 114b, 114c, 114d); the first electrode (110) and the second electrode (120) are disposed above the pair of folds (114a, 114b, 114c, 114d); both the first electrode (110) and the second electrode (120) are in electrical contact with both of the pair of folds (114a, 114b, 114c, 114d); the distance between the pairs of folds (114a, 114b, 114c, 114d) is at most 0.2 μm; 1. A superconducting device adapted to support a current between the first electrode (110) and the second electrode (120) through the folded region (112) having a resistivity at least 100 times lower than the bulk resistivity of graphite, with the folded region (112) at room temperature.

2. a third electrode (130) disposed on the at least one uppermost atomic layer (102) and spaced apart from the first electrode (110) and the second electrode (120); the at least one top atomic layer (102) includes a second folded region (122) disposed between the second electrode (120) and the third electrode (130); the second pleat region (122) includes a second plurality of pleats including a second pair of pleats (114a, 114b, 114c, 114d); both the second electrode (120) and the third electrode (130) are in electrical contact with both of the folds of the second pair; 10. The superconducting device of claim 1, wherein the distance between the corrugations of the second pair is at most 0.2 μm.

3. a plurality of electrodes (110, 120, 130, 140, 160, 170) including the first electrode (110) and the second electrode (120), the plurality of electrodes (110, 120, 130, 140, 160, 170) including at least four electrodes (110, 120, 130, 140, 160, 170) spaced apart from one another; a plurality of pleated regions (112, 112d, 122, 122d, 132, 132d, 142, 142d, 152, 152d) of the at least one top atomic layer (102), including the pleated region (112) and including at least three pleated regions (112, 112d, 122, 122d, 132, 132d, 142, 142d, 152, 152d); The fold regions (112, 112d, 122, 122d, 132, 132d, 142, 142d, 152, 152d) included in the plurality of fold regions (112, 112d, 122, 122d, 132, 132d, 142, 142d, 152, 152d) are Associated with each pair of electrodes of the plurality of electrodes (110, 120, 130, 140, 160, 170), disposed between each associated pair of electrodes (110, 120, 130, 140, 160, 170); each of the plurality of folds (114) including a respective pair of folds, wherein both of the electrodes (110, 120, 130, 140, 160, 170) of each associated pair are in electrical contact with both of the folds of each pair, and the distance between the folds of each pair is at most 0.2 μm; 2. The superconducting device of claim 1, wherein any two electrodes (110, 120, 130, 140, 160, 170) of the plurality of electrodes (110, 120, 130, 140, 160, 170) are electrically interconnected via the folded region (112, 112d, 122, 122d, 132, 132d, 142, 142d, 152, 152d) and / or the electrode (110, 120, 130, 140, 160, 170).

4. 2. The superconducting device of claim 1, wherein the pair of the corrugations (114a, 114b, 114c, 114d) comprises parallel sections (116a, 116b, 116c).

5. 2. The superconducting device of claim 1, wherein one of the pair of corrugations extends along a first corrugation direction at a junction to the first electrode, the first electrode having a first edge defining a boundary of the corrugated region, the first edge being perpendicular to the first corrugation direction.

6. the plurality of pleats includes a high-density pleat array (114d) having at least one pleat; 2. The superconducting device of claim 1, wherein the plurality of corrugations includes adjacent corrugations and opposite adjacent corrugations on opposite sides of the at least one corrug of the high-density corrugation array, and wherein a distance between the at least one corrug and the adjacent corrug and a distance between the at least one corrug and the opposite adjacent corrug are both at most 0.2 μm.

7. 7. The superconducting device of claim 6, wherein the pair of pleats and / or the at least one pleat of the dense pleat array (114d) extend through all atomic layers of the at least one top atomic layer (102), the at least one top atomic layer (102) comprising at least three top atomic layers (102a, 102b, 102c).

8. The graphite structure (100) comprises: at least two bulk atomic layers (214) below the at least one top atomic layer (102) having a bulk layer spacing (216) between adjacent bulk atomic layers (214); a pleat layer spacing (206) within the pleat (114) between an atomic layer (102a) of the at least one top atomic layer (102) and an adjacent layer (102b) of the at least one top atomic layer (102); 2. The superconducting device of claim 1, wherein the pleated layer spacing (206) exceeds the bulk layer spacing (216), particularly by at least 0.5%, or at least 1%, or at least 1.5%.

9. The superconducting device of claim 8, wherein the at least two bulk atomic layers (214) are essentially flat.

10. 7. The superconducting device of claim 6, wherein the ratio of the height (202) to the width (204) of the pleats (114a, 114b, 114c, 114d) of the pairs and / or the pleats (114d) of the dense pleat array (114d) is at least 0.5, in particular at least 0.7, in particular at least 0.9, in particular at least 1.1 or at least 1.

3.

11. 2. The superconducting device of claim 1, wherein the pairs of the corrugations (114a, 114b, 114c, 114d) form branches (128) and / or intersections (126).

12. The plurality of folds comprises at least two pairs of folds, in particular at least three pairs of folds or at least four pairs of folds; both the first electrode (110) and the second electrode (120) are in electrical contact with both of the respective folds of the pair; A superconducting device according to any one of claims 1 to 11, wherein each distance between each corrugation of said pair is at most 0.2 µm.

13. 1. Use of a folded region (112) of at least one top atomic layer (102) of a graphite structure (100) as a superconducting device having a critical temperature of at least room temperature, comprising: The pleated region (112) includes a plurality of pleats (114) having pairs of pleats (114a, 114b, 114c, 114d), The distance between the pairs of folds (114a, 114b, 114c, 114d) is at most 0.2 μm.

14. 1. A method of manufacturing a superconducting device, comprising: providing a pleated region (112) of at least one top atomic layer (102) of the graphite structure (100), the pleated region (112) including a plurality of pleats (114) having pairs of pleats (114a, 114b, 114c, 114d), wherein the distance between the pleats (114a, 114b, 114c, 114d) of the pairs is at most 0.2 μm; disposing a first electrode (110) on said at least one uppermost atomic layer (102) and in electrical contact with said pair of said folds (114a, 114b, 114c, 114d); and disposing a second electrode (120) on the at least one top atomic layer (102) in electrical contact with the pair of folds (114a, 114b, 114c, 114d), wherein the second electrode (120) is spaced apart from the first electrode (110) along the at least one top atomic layer (102) and the fold region (112) is located between the first electrode (110) and the second electrode (120).

15. 1. A superconducting device, comprising: a graphite structure (100) having at least one top atomic layer (102); a first electrode (110) disposed on the at least one uppermost atomic layer (102); a second electrode (120) disposed on the at least one uppermost atomic layer (102) and spaced apart from the first electrode (110); a pleated region (112) of the at least one uppermost atomic layer (102), the pleated region (112) being disposed between the first electrode (110) and the second electrode (120), the pleated region (112) including a plurality of pleats including pairs of pleats (114a, 114b, 114c, 114d); the first electrode (110) and the second electrode (120) are disposed above the pair of folds (114a, 114b, 114c, 114d); both the first electrode (110) and the second electrode (120) are in electrical contact with both of the pair of folds (114a, 114b, 114c, 114d); the distance between the pairs of folds (114a, 114b, 114c, 114d) is at most 0.2 μm; the plurality of pleats includes at least two pairs of pleats; both the first electrode (110) and the second electrode (120) are in electrical contact with both of the at least two pairs of respective folds; A superconducting device, wherein each distance between each of said at least two pairs of corrugations is at most 0.2 μm.

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