Method for designing high-temperature superconducting materials using thermal decoupling phenomenon, and development of room-temperature superconducting materials using same

Abstract

A method for designing high-temperature superconducting materials according to an embodiment of the present invention comprises, in a layered superconductor including an atomic layer containing an alkali metal or alkaline earth metal and a conductive layer containing one or more materials selected from the periodic table: a step for identifying conditions for thermal decoupling occurring between the atomic layer and the conductive layer; and a step for predicting or controlling the superconducting critical temperature (Tc) of a material on the basis of the thermal decoupling conditions.

Description

Design method for high-temperature superconducting materials using thermal decoupling phenomenon and development of room-temperature superconducting materials through the same

[0001] The present invention relates to the field of design and development of superconducting materials, and in particular to a technology for designing a new superconducting material having a layered structure and comprising an alkali metal or an alkaline earth metal.

[0002] Superconductivity was first discovered in mercury in 1911 by the Dutch physicist Heike Kamerlingh Onnes, and it refers to the phenomenon in which the electrical resistance of a material completely disappears below a certain temperature. Early superconducting materials exhibited superconductivity only at extremely low temperatures close to absolute zero, which posed a significant limitation to practical applications. The BCS theory, proposed by Bardeen, Cooper, and Schrieffer in 1957, explained superconductivity through electron-phonon interactions, but the upper limit of the superconducting critical temperature predicted by this theory was only about 25K.

[0003] The discovery of high-temperature superconducting materials by Bednorz and Muller in the mid-1980s marked a new turning point in superconductivity research. Copper oxide-based high-temperature superconductors exhibited high critical temperatures exceeding the predictions of the aforementioned BCS theory, and the highest superconducting critical temperature reported to date under atmospheric pressure conditions is approximately 140 K. Since then, various unconventional superconducting materials have been discovered, including iron-based superconductors, infinite-layer nickel oxide, high-pressure hydrides, and magic-angle twisted bilayer graphene.

[0004] However, these high-temperature superconducting materials exhibit several unresolved challenges. First, the linear thermal resistivity (ρ ∝ T) and Planckian dissipation (ħ / τ = αk) observed in strange metals BThe fundamental cause of the T) phenomenon has not been revealed. Second, the linear relationship between the superconducting critical temperature and the Fermi temperature observed in the Uemura plot (T c ∝ T F There is a lack of theoretical explanation for ). Third, the mechanism of the superconducting dome phenomenon according to doping concentration has not been clearly elucidated. Fourth, the correlation between the pseudogap phenomenon and superconductivity is unclear.

[0005] Due to these fundamental lacks of understanding, it was perceived as nearly impossible to rationally design new materials with superconducting critical temperatures at or near room temperature.

[0006] The present invention aims to solve the aforementioned conventional problems, and one objective of the present invention is to address the linear thermal resistivity (ρ ∝ T) of the Strange Metal phase and Planckian Dissipation (ħ / τ = αk) appearing in high-temperature superconducting materials. B T) It is to provide a method for identifying the fundamental physical mechanism of the phenomenon.

[0007] In addition, another objective of the present invention is to [do not provide] a linear relationship (T) between the superconducting critical temperature and the Fermi temperature observed in the Uemura plot. c ∝ T F It provides a theoretical basis for quantitatively predicting ).

[0008] In addition, another objective of the present invention is to provide a method to control the superconducting critical temperature by clearly identifying the mechanism of the superconducting dome phenomenon according to doping concentration.

[0009] In addition, another objective of the present invention is to provide a methodology for systematically designing and exploring high-temperature superconducting materials having a remarkably high superconducting critical temperature by utilizing the thermal decoupling phenomenon occurring in layered materials containing alkali metals and alkaline earth metals.

[0010] Furthermore, another objective of the present invention is to provide a method for developing a new material capable of realizing a superconducting critical temperature at or near room temperature while minimizing experimental trial and error through computer simulation-based material design technology.

[0011] However, the objectives of the present invention are not limited to those mentioned above, and may be extended in various ways without departing from the spirit and scope of the invention. Furthermore, those skilled in the art to which the present invention pertains will clearly understand other objectives of the present invention from the following detailed description, and such objectives should also be interpreted as being included within the scope of the rights of the present invention.

[0012] A method for designing a high-temperature superconducting material proposed in one embodiment of the present invention includes the steps of identifying thermal decoupling conditions occurring between an atomic layer and a conductive layer in a layered superconductor comprising an atomic layer comprising an alkali metal or alkaline earth metal and a conductive layer in which electron transport occurs, and predicting or controlling the superconducting critical temperature of the material based on the thermal decoupling conditions.

[0013] The step of determining the above thermal decoupling conditions may include a step of confirming the state in which the alkali metal or alkaline earth metal atoms are electronically separated from the conductive layer through density functional theory calculations.

[0014] The step of determining the above thermal decoupling conditions may include performing molecular dynamics simulations to calculate the effective temperature for each layer and confirming that the effective temperature of the alkali metal or alkaline earth metal atomic layer is different from the effective temperature of the conductive layer.

[0015] The relationship between the effective temperature of the alkali metal or alkaline earth metal atomic layer and the effective temperature of the conductive layer may satisfy a quadratic function relationship T1 = a * T2² + b (where a and b are constants).

[0016] The step of determining the above thermal decoupling conditions may include verifying the thermal decoupling phenomenon through the phonon dispersion relation analyzed using a temperature-dependent phonon calculation method and the softening phenomenon of a specific phonon mode of the alkali metal or alkaline earth metal.

[0017] The step of determining the above thermal decoupling conditions may include confirming that the temperature-dependent component contribution of internal energy by the low-frequency phonon mode of the alkali metal or alkaline earth metal atom increases as the temperature decreases.

[0018] The above design method may include a step of improving the superconducting critical temperature by controlling the thermal decoupling effect by adjusting the distance between the alkali metal or alkaline earth metal atomic layer and the conductive layer.

[0019] The above design method may further include a step of verifying the phenomenon of a high-temperature superconducting material designed based on unresolved challenges of high-temperature superconducting materials that were not theoretically solved in the past.

[0020] The above verification step may include a step of determining whether the designed superconducting material satisfies the linear relationship between the superconducting critical temperature and the Fermi temperature observed in the Uemura plot using the thermal decoupling effect.

[0021] The verification step may include a step of predicting the superconducting dome phenomenon by analyzing structural changes between the alkali metal or alkaline earth metal atomic layer and the conductive layer according to changes in doping concentration.

[0022] The alkali metal or alkaline earth metal comprises one or more metals selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, francium, magnesium, calcium, strontium, barium, and radium, and the conductive layer may comprise a planar or bulky form comprising one or more elements selected from the periodic table.

[0023]

[0024] A high-temperature superconducting material proposed in another embodiment of the present invention comprises a layered structure of an atomic layer containing an alkali metal or an alkaline earth metal and a conductive layer in which electron transport occurs, and is characterized by having different effective temperatures due to thermal decoupling occurring between the atomic layer and the conductive layer.

[0025] The alkali metal or alkaline earth metal comprises one or more metals selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, francium, magnesium, calcium, strontium, barium, and radium, and the conductive layer may comprise a structure having a planar or bulky form comprising one or more elements selected from the periodic table.

[0026] The relationship between the effective temperature of the atomic layer and the effective temperature of the conductive layer may satisfy the quadratic function relationship T1 = a * T2² + b (where a and b are constants).

[0027] The above alkali metal or alkaline earth metal atoms can form a state that is electronically separated from the conductive layer.

[0028] The contribution of the temperature-dependent component of internal energy by the low-frequency phonon mode of the above atomic layer can increase below the decoupling temperature.

[0029] The above superconducting material may be designed by a design method according to one embodiment of the present invention described above.

[0030]

[0031] A method for searching for high-temperature superconducting materials using computer simulation, proposed in another embodiment of the present invention, comprises the steps of: confirming an electronic separation state by performing density functional theory calculations on candidate materials including alkali metals or alkaline earth metals; verifying thermal decoupling conditions by performing molecular dynamics simulations on said candidate materials; predicting a superconducting critical temperature for said candidate materials in which thermal decoupling conditions have been confirmed; and selecting a candidate material in which the predicted superconducting critical temperature is greater than or equal to a reference value as a high-temperature superconducting material.

[0032] The step of predicting the superconducting critical temperature may include a step of deriving the optimal critical temperature by calculating the change in the thermal decoupling effect according to the change in distance between the alkali metal or alkaline earth metal atomic layer and the conductive layer.

[0033] A design method for a high-temperature superconducting material based on thermal decoupling according to one embodiment of the present invention has the effect of identifying that the linear thermal resistivity observed on the Strange Metal is actually a phenomenon in which the Fermi liquid behavior (ρ ∝ T²) of the conductive layer appears as apparent linear behavior through temperature conversion, by forming a quadratic function relationship T1 = a * T2² + b between the measured temperature and the actual conductive layer temperature due to thermal separation between the alkali metal or alkaline earth metal atomic layer and the conductive layer.

[0034] A method for designing a high-temperature superconducting material according to one embodiment of the present invention relates the temperature relationship T1 = a * T2² + b due to thermal decoupling to the Planckian Dissipation equation ħ / τ = αk B By substituting into T, ħ / τ ∝ kB Derive the relationship T2², and through this, T c ≒ (α / 4A)T F By deriving the relationship equation, it is possible to quantitatively predict the Uemura relationship.

[0035] A high-temperature superconducting material design method according to one embodiment of the present invention has the effect of quantitatively predicting and controlling structural changes and superconducting dome phenomena according to changes in doping concentration by identifying that the thermal decoupling effect is strengthened and the superconducting critical temperature is improved as the distance between the alkali metal or alkaline earth metal and the conductive layer increases.

[0036] A material search method according to one embodiment of the present invention has the effect of efficiently selecting candidate materials predicted to have a high superconducting critical temperature without experimental trial and error by undergoing a stepwise screening process that confirms the electronic separation state of alkali metals / alkali earth metals through density functional theory calculations and verifies thermal decoupling through Ab initio molecular dynamics simulations.

[0037] The thermal decoupling principle according to one embodiment of the present invention can be commonly applied to various superconducting material groups such as cuprates, pnictides, hydrides, nickelates, and kagome when alkali metals or alkaline earth metals are included, thereby providing a universal high-temperature superconducting material design methodology.

[0038] A design method according to one embodiment of the present invention has the effect of providing a theoretical foundation for the development of innovative new materials having a superconducting critical temperature at or near room temperature by presenting structural conditions that can maximize the thermal decoupling effect.

[0039] Furthermore, the aforementioned principle proposed in the embodiments of the present invention has the effect of enabling a new perspective on the implementation of high-temperature superconductors, completely departing from the conventional view of high-temperature superconductors.

[0040]

[0041] However, the effects of the present invention are not limited to those mentioned above, and various additional effects may occur within the scope and spirit of the invention. Furthermore, those skilled in the art to which the present invention pertains will clearly recognize other effects of the invention from the following detailed description and embodiments, and such effects should also be interpreted as being included within the technical scope of the present invention. Moreover, the thermal decoupling principle of the present invention is expected to produce unexpected technical effects in various application fields not explicitly described.

[0042] Figure 1 is a phase diagram image according to doping concentration and temperature in a superconductor according to one embodiment of the present invention.

[0043] FIG. 2 is a schematic diagram showing the crystal structure of a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention.

[0044] FIG. 3 shows B in a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention. 1g and A g This is a graph showing the frequency change of phonon modes according to temperature, and a structural diagram illustrating the vibration directions of the corresponding modes.

[0045] Figure 4 is a graph showing the effective temperatures per layer extracted through molecular dynamics simulation in a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention. Figure 4 shows that the BaO layer, the CuO2 layer, the Y layer, and the CuO chain layer have different temperatures and that a thermal decoupling phenomenon occurs.

[0046] FIG. 5 is a graph showing the phonon dispersion relation and the internal energy contribution (TDPIE) by the phonon mode of Ba atoms calculated at different temperatures (300K, 90K, 30K) in a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention. FIG. 5 is an image showing that when the temperature is high, phonons contribute evenly to the internal energy from low to high frequencies, but as the temperature decreases, the contribution in the low-frequency region increases predominantly, and in particular, the phonon mode of Ba atoms appears prominently.

[0047] FIG. 6 is a graph showing the internal energy contribution (TDPIE) of each element according to temperature in a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention, and a schematic diagram showing the electron density distribution of the Ba atom and its surroundings. FIG. 6 shows that as the temperature decreases, the contribution of Ba increases significantly, showing thermal separation, and at the same time, the electron cloud of Ba is separated from other elements, indicating that electronic decoupling occurs.

[0048] FIG. 7 is a graph showing the change in the distance between Ba and CuO2 and the change in the superconducting critical temperature according to the doping concentration in a copper oxide superconductor (YBa2Cu3O7) according to one embodiment of the present invention. It is a graph explaining that as the distance between Ba and CuO2 increases with increasing doping concentration, thermal decoupling is strengthened, which leads to an increase in the superconducting critical temperature.

[0049]

[0050] The embodiments of the present invention are illustrative for the purpose of explaining the technical concept of the present invention. The scope of rights according to the present invention is not limited to the embodiments presented below or the specific description thereof.

[0051] All technical and scientific terms used in this invention, unless otherwise defined, have the meaning generally understood by those skilled in the art to which this invention pertains. All terms used in this invention are selected for the purpose of further explaining this invention and are not selected to limit the scope of rights according to this invention.

[0052] Expressions such as "comprising," "having," "having," etc. used in the present invention should be understood as open-ended terms implying the possibility of including other embodiments, unless otherwise stated in the phrase or sentence containing such expressions.

[0053] Unless otherwise stated, singular expressions described in the present invention may include the meaning of the plural form, and this applies likewise to singular expressions described in the claims.

[0054]

[0055] The present invention relates to identifying the thermal decoupling phenomenon occurring between an atomic layer containing an alkali metal or alkaline earth metal and a conductive layer where electron transport takes place, and to a method for systematically designing high-temperature superconducting materials by utilizing this. Specific embodiments and implementation processes of the present invention are described in detail below.

[0056] In one embodiment of the present invention described below, the atomic layer and the conductive layer are explained as being formed as a single planar concept; however, the technical concept regarding the atomic layer and the conductive layer proposed in the present invention is not necessarily limited to layers formed as 2D planes. Both the atomic layer and the conductive layer, or either one thereof, may be 2D layers formed by the aggregation of atoms, but may include any structure having volume. In the present invention, a structure having volume does not necessarily have to be a structure such as a rectangular prism formed by stacking planes, but is described as a concept including a cluster of atoms having any volume. For convenience, the present invention will be described using the concept of a layer.

[0057]

[0058] In the field of high-temperature superconducting material research, various unresolved challenges have existed for decades. As illustrated in Fig. 1, major phenomena observed in the phase diagrams of high-temperature superconductors, particularly the linear thermal resistivity (ρ ∝ T) in the Strange Metal phase, the linear relationship between the superconducting critical temperature and the Fermi temperature in the Uemura plot, the superconducting dome phenomenon depending on doping concentration, and the pseudo-gap phenomenon, were difficult to explain clearly with existing theories. As the fundamental causes of these phenomena remained unknown, it was nearly impossible to rationally design superconducting materials at or near room temperature.

[0059] In particular, the upper limit of the superconducting critical temperature predicted by the BCS theory proposed by Bardeen, Cooper, and Schrieffer in 1957 was only about 25K, and while copper oxide-based high-temperature superconductors discovered since then have shown performance exceeding this prediction, their mechanism remained a mystery. To date, the highest superconducting critical temperature reported under atmospheric pressure conditions has remained at around 140K, meaning that a significant technological breakthrough was required to realize practical room-temperature superconductors.

[0060]

[0061] Discovery and Definition of Thermal Decoupling Phenomenon

[0062] The core concept proposed in this invention is the phenomenon of thermal decoupling. This refers to a special thermodynamic state in which the two layers have different effective temperatures, occurring between an alkali metal or alkaline earth metal atomic layer and a conductive layer responsible for electron transport in a layered superconductor. Taking the YBa2Cu3O7 (YBCO) structure illustrated in Fig. 2 as an example, this thermal separation phenomenon occurs between the BaO plane containing barium (Ba) atoms and the CuO2 plane responsible for electron transport.

[0063]

[0064] The fundamental physical cause of this phenomenon has been identified as being due to two main mechanisms. First, the atoms of alkali metals or alkaline earth metals form a state of being electronically isolated from the conductive layer. As can be seen from the charge density distribution analysis results in Figure 6, barium atoms are found to be electronically isolated from copper and oxygen atoms. Second, the softening of low-frequency phonon modes of alkali metals or alkaline earth metals weakens the interlayer bonding, reducing thermal transport and inducing a state of thermal isolation.

[0065]

[0066] The condition under which thermal decoupling occurs is the decoupling temperature (T dec It can be quantified as a concept.

[0067] In one embodiment of the present invention, the temperature of YBCO is calculated to be approximately 216.3K, and below this temperature, a quadratic function relationship of T1 = a * T2² + b (where a = 2.31 * 10³ and b = 107.6 in the case of YBCO) can be established between the effective temperature of the BaO plane (T1) and the effective temperature of the CuO2 plane (T2).

[0068]

[0069] Confirmation of electronic separation through DFT calculation

[0070] In the first embodiment of the present invention, the electronic separation state of alkali metal or alkaline earth metal atoms may be confirmed through density functional theory (DFT) calculations. This may be a key process for understanding the electronic basis of thermal decoupling phenomena, and an example of the DFT calculations performed by the inventors is described in detail below.

[0071] First, the plane wave pseudopotential was calculated using the Vienna Ab initio Simulation Package (VASP) code. Next, the Perdew-Burke-Ernzerhof functional of the Generalized Gradient Approximation (GGA) was applied, with the energy cutoff value of the plane wave basis set to 400 eV. The DFT-D3 method was used to account for van der Waals long-range dispersion forces. A 1x1x1 grid was adopted as the computational structure, and k-point sampling of a 9x9x3 grid was performed in the Brillouin region.

[0072] Charge density analysis confirmed that barium atoms exhibit an electron distribution clearly separated from copper and oxygen atoms. This is understood to mean that barium atoms possess an electronic environment independent of the conductive properties of the CuO2 plane. Considering that free electrons play a crucial role in heat transport within a material, this electronic separation provides a condition for the thermal properties to be separated between the barium atomic layer and the CuO2 plane.

[0073]

[0074] Layer-by-layer temperature extraction through molecular dynamics simulation

[0075] According to one embodiment of the present invention, the method may include calculating the effective temperature for each layer through Ab initio molecular dynamics (AIMD) simulation. As shown in FIG. 4, this process can quantitatively confirm that each layer actually has a different effective temperature.

[0076] AIMD simulations can be performed under various temperature conditions using a thermostat (a Nose-Hoover thermostat, according to one example). In one embodiment of the present invention, the inventors set the simulation time interval to 1 fs and performed calculations for 60 ps at each temperature within the NVT ensemble. Initially, simulations were performed for 60 ps at 300 K, then the temperature was lowered by 10 K increments while controlling the temperature for 5 ps, and simulations were continued for 60 ps at each temperature.

[0077] At this point, the kinetic energy of each atom is calculated at each time step, and the kinetic energy-temperature relationship (½mv² = 3 / 2 k B The effective temperature per layer can be derived using T).

[0078] As can be seen in Figure 4, under 300K simulation conditions, all layers exhibit almost the same effective temperature, but under 90K and 30K conditions, the effective temperature of the BaO plane was found to be significantly higher than that of the other planes. In particular, under 30K conditions, the effective temperature of the BaO plane reached approximately 60K, whereas the CuO2 plane and the Y layer remained at a level of approximately 30K or lower. Additionally, as can be seen in (df) of Figure 4, it was confirmed that within the BaO plane, the Ba atoms, in particular, had a higher effective temperature.

[0079] These results clearly demonstrate that under low-temperature conditions, the barium atomic layer is actually thermally separated from other layers and maintains an independent thermodynamic state.

[0080]

[0081] Phonon Variance and TDPIE Analysis

[0082] In one embodiment of the present invention, a phonon dispersion relation analysis using a temperature-dependent phonon calculation method can be used. As shown in FIG. 5, through this analysis, the lattice dynamic basis of the thermal decoupling phenomenon can be confirmed.

[0083] As can be seen in FIG. 3, in one embodiment of the present invention, B 1g The phonon mode (out-of-plane vibration of CuO2 planar oxygen) is approximately 1.3 cm when the temperature decreases from 300 K to 20 K. -1 It decreased. What is even more noteworthy is A g As a phonon mode (out-of-plane vibration of a barium atom), approximately 70 cm in the same temperature range -1 The phonon softening phenomenon was significantly reduced. This indicates that the bonding between the barium atom and the CuO2 plane is weakened, resulting in reduced interlayer heat transport.

[0084] As a result of the TDPIE contribution analysis, it can be confirmed that the contribution of barium atoms increases significantly with decreasing temperature. As shown in Fig. 5, barium atoms mainly contribute to low-frequency phonon modes, and this contribution showed a maximum value near 30K as shown in Fig. 6. This indicates that at low temperatures, the contribution to internal energy varies for each type of atom, and that barium atoms, in particular, exhibit unique thermodynamic behavior.

[0085]

[0086] Solving (verifying) existing high-temperature superconducting challenges

[0087] The thermal decoupling phenomenon discovered in this invention can provide an integrated interpretation of the major challenges in existing high-temperature superconductor research. In embodiments of this invention, this can be utilized as a method to verify designed superconducting materials.

[0088]

[0089] According to the design method for high-temperature superconducting materials proposed in the present invention, first, the Planckian dissipation phenomenon (ħ / τ = αk) observed on a strange metal B A new interpretation of T is possible. Although τ must be determined by the conductive layer, the measured temperature T corresponds to a surface containing stable alkali metals or alkaline earth metals. Substituting the quadratic function relationship into the Planckian dissipation equation yields ħ / τ ∝ 2.31 × 10⁻⁶ -3 T 2 It becomes CuO2, so in reality, the conductive layer exhibits Fermi liquid behavior (ρ ∝ T 2 It can be seen that it exhibits ). In other words, the apparent linear thermal resistivity is due to the temperature conversion effect.

[0090] Second, the superconducting critical temperature (T) observed in the Uemura plot c ) and Fermi temperature (T F The linear relationship between ) can also be quantitatively derived. By applying the continuity condition of Fermi liquid resistivity and Planckian dissipation, T c ≒ (α / 4A)T F A relational expression can be obtained, and as a result of the inventors performing actual calculations in one embodiment of the present invention, T c / T F = 0.044, which was confirmed to be in very good agreement with the experimental value of 0.042.

[0091] Third, the superconducting dome phenomenon depending on the doping concentration can also be interpreted from the perspective of thermal decoupling.

[0092] As shown in Fig. 7, YBa2Cu3O xWhen the oxygen content increases from x = 6 to 7, the distance between the Ba-CuO2 planes increases, which strengthens the thermal decoupling between the Ba and CuO2 layers. In the embodiments of the present invention, the inventors confirmed that this structural change strengthens the thermal decoupling effect, leading to an improvement in the superconducting critical temperature, and fully explained the trend of the superconducting critical temperature according to the doping concentration as shown in FIG. 7.

[0093]

[0094] Applications in material design and prediction of superconducting properties

[0095] The material design method proposed in the embodiments of the present invention follows the following systematic approach. First, the electronic isolation state can be verified by performing DFT calculations on candidate materials containing alkali metals or alkaline earth metals. In this process, it can be evaluated whether the corresponding atoms are sufficiently isolated from the conductive layer through charge density distribution analysis.

[0096] Next, thermal decoupling conditions can be verified through AIMD simulation. At this time, it may be necessary to calculate the effective temperature for each layer to check whether a significant temperature difference occurs between the alkali metal or alkaline earth metal atomic layer and the conductive layer. In particular, it may be necessary to verify whether the temperature relationship between the two layers follows a quadratic function below the decoupling temperature.

[0097] In one embodiment, through phonon analysis using a temperature-dependent phonon calculation method, the softening phenomenon of low-frequency phonon modes of alkali metals or alkaline earth metals can be observed, and changes in the TDPIE contribution of low-frequency phonon modes can be tracked. Through this analysis, the weakening of interlayer bonding and the reduction in thermal transport can be quantitatively evaluated.

[0098] Finally, the superconducting critical temperature can be predicted using the previously derived relationships. In one embodiment, optimal conditions can be found by calculating the change in the thermal decoupling effect according to the change in distance between the alkali metal or alkaline earth metal atomic layer and the conductive layer. The process may include selecting candidate materials as high-temperature superconducting materials if the predicted results are above a reference value.

[0099]

[0100] Specific Example: YBCO System

[0101] As an example of an embodiment of the present invention, the YBa2Cu3O7 system can be cited. In this material, the barium atomic layer can serve as an alkaline earth metal atomic layer, and the CuO2 plane can serve as a conductive layer.

[0102] Structurally, it has an orthogonal structure (15.308 Å * 15.652 Å * 11.738 Å), which is a structure extended by 0.08 Å in the c-axis direction compared to the ab initio optimized structure.

[0103] In one embodiment, the inventors, based on the results of a thermal decoupling analysis, calculated that the decoupling temperature is 216.3K, and at this temperature or below, T BaO = 2.31 * 10 -3 T CuO2 2 It was confirmed that the relationship + 107.6 holds. In the phonon analysis, B 1g The mode exhibited rapid softening near 70K, which coincided with the superconducting critical temperature (~90K) observed in experiments. Also, A g In the case of the mode, much stronger softening was observed, which was a result supporting the thermal separation of the barium atomic layer.

[0104]

[0105] Expansion into other superconducting material groups

[0106] In one embodiment of the present invention, the principle described above may be applicable to groups of superconducting materials other than YBCO. In cuprate series containing strontium (Sr), Sr atoms can perform a role similar to that of Ba atoms. For example, Bi2Sr2CaCu2O 8+δ A similar correlation between the Sr-CuO2 plane distance and the superconducting critical temperature can be observed in other Sr-containing cuprates as well.

[0107] Furthermore, similar thermal decoupling phenomena may occur in nickelates, hydrides, kagomes, and other layered superconductors when alkali metal or alkaline earth metal elements are included. When considering these aspects, it is evident that the embodiments of the present invention are not limited to specific materials and provide general design principles.

[0108]

[0109] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

1. A layered superconductor comprising an atomic layer comprising an alkali metal or an alkaline earth metal and a conductive layer comprising one or more materials selected from the periodic table, A step of identifying the thermal decoupling conditions occurring between the atomic layer and the conductive layer; and Based on the above thermal decoupling conditions, the superconducting critical temperature (T) of the material c A step of predicting or controlling ); comprising, Design method for high-temperature superconducting materials.

2. In Paragraph 1, The step of identifying the above thermal decoupling conditions is, The method includes the step of confirming, through density functional theory (DFT) calculations, that the alkali metal or alkaline earth metal atoms are in a state of being electronically separated from the conductive layer. Design method for high-temperature superconducting materials.

3. In Paragraph 1, The step of identifying the above thermal decoupling conditions is, The method includes the step of performing molecular dynamics simulations to calculate the effective temperature for each layer and confirming that the effective temperature of the alkali metal or alkaline earth metal atomic layer is different from the effective temperature of the conductive layer. Design method for high-temperature superconducting materials.

4. In Paragraph 1, The relationship between the effective temperature (T1) of the alkali metal or alkaline earth metal atomic layer and the effective temperature (T2) of the conductive layer is T1 = a * T2 2 That which satisfies that it is a function of + b (where a and b are constants), Design method for high-temperature superconducting materials.

5. In Paragraph 1, The step of identifying the above thermal decoupling conditions is, The method includes the step of verifying the thermal decoupling phenomenon through the phonon dispersion relation analyzed using a temperature-dependent phonon calculation method and the softening phenomenon of low-frequency phonon modes of alkali metals or alkaline earth metals. Design method for high-temperature superconducting materials.

6. In Paragraph 1, The step of identifying the above thermal decoupling conditions is, The method includes the step of confirming that the contribution of the temperature-dependent component (TDPIE) of internal energy by the low-frequency phonon mode of the alkali metal or alkaline earth metal atom increases with decreasing temperature. Design method for high-temperature superconducting materials.

7. In Paragraph 1, The method includes the step of improving the superconducting critical temperature by controlling the thermal decoupling effect by adjusting the distance between the alkali metal or alkaline earth metal atomic layer and the conductive layer. Design method for high-temperature superconducting materials.

8. In Paragraph 1, The method further includes a step of verifying the phenomenon of a high-temperature superconducting material designed based on unresolved challenges of high-temperature superconducting materials that were not theoretically solved in the past. Design method for high-temperature superconducting materials.

9. In Paragraph 8, The above verification step is, The superconducting critical temperature (T) observed in the Uemura plot by the designed superconducting material utilizing the above thermal decoupling effect c ) and Fermi temperature (T F Linear relationship T between ) c ≒ (α / 4A)T F It includes a step of checking whether it satisfies, Design method for high-temperature superconducting materials.

10. In Paragraph 8, The above verification step is, The method includes the step of predicting a superconducting dome phenomenon by analyzing structural changes between the alkali metal or alkaline earth metal atomic layer and the conductive layer according to changes in doping concentration. Design method for high-temperature superconducting materials.

11. In Paragraph 1, The above alkali metal or alkaline earth metal comprises one or more selected from metals consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and The above conductive layer comprises a structure having a planar or bulky shape, Design method for high-temperature superconducting materials.

12. An atomic layer comprising an alkali metal or an alkaline earth metal; and A structure comprising a conductive layer comprising one or more materials selected from the periodic table; and Characterized by thermal decoupling occurring between the atomic layer and the conductive layer, resulting in different effective temperatures. High-temperature superconducting material.

13. In Paragraph 12, The above alkali metal or alkaline earth metal comprises one or more selected from metals consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and The above conductive layer comprises one or more elements selected from the periodic table, High-temperature superconducting material.

14. In Paragraph 12, The relationship between the effective temperature (T1) of the atomic layer and the effective temperature (T2) of the conductive layer satisfies the functional relationship T1 = a * T2² + b (where a and b are constants). High-temperature superconducting material.

15. In Paragraph 12, The above alkali metal or alkaline earth metal atoms form a state of being electronically separated from the conductive layer, High-temperature superconducting material.

16. In Paragraph 12, Decoupling temperature (T dec ) In the following, the contribution of the temperature-dependent component of internal energy due to the low-frequency phonon mode of the above atomic layer increases, High-temperature superconducting material.

17. In Paragraph 12, The above superconducting material is Designed by the design method of Paragraph 1, High-temperature superconducting material.

18. In a method for searching for high-temperature superconducting materials using computer simulation, A step of confirming the electronic separation state by performing density functional theory (DFT) calculations on candidate materials containing alkali metals or alkaline earth metals; A step of verifying thermal decoupling conditions by performing molecular dynamics simulations on the above candidate material; A step of predicting the superconducting critical temperature for a candidate material in which the above thermal decoupling conditions have been confirmed; and A step of selecting candidate materials as high-temperature superconducting materials in which the predicted superconducting critical temperature is greater than or equal to a reference value; comprising Method for searching for high-temperature superconducting materials using computer simulation.

19. In Paragraph 18, The step of predicting the superconducting critical temperature above is, The method includes the step of deriving an optimal critical temperature by calculating the change in the thermal decoupling effect according to the change in distance between the alkali metal or alkaline earth metal atomic layer and the conductive layer. Method for searching for high-temperature superconducting materials using computer simulation.

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