Tunneling spectroscopy apparatus through edge of two dimension material

Abstract

An embodiment of the present invention relates to a tunneling spectroscopy device through the edge of a two-dimensional material. According to one embodiment of the present invention, a tunneling spectroscopy device through the edge of a two-dimensional material to be spectroscopically analyzed is provided, comprising: a tunneling probe that forms a tunneling junction in contact with the two-dimensional material and a spectrometer that analyzes physical property data detected through the tunneling probe; wherein the tunneling probe contacts the edge of the two-dimensional material.

Description

Technology Field

[0001] An embodiment of the present invention relates to a tunneling spectroscopy device through the edge of a two-dimensional material, and more specifically, to a tunneling spectroscopy device that performs tunneling spectroscopy by contacting a probe to the edge of a two-dimensional material. Background Technology

[0003] Light can be used as a tool to disrupt the original equilibrium in order to create new quantum states. One example of this is Floquet engineering, which dynamically controls the properties of quantum materials through time-cycle electromagnetic driving. Floquet states allow for rapid and comprehensive control of the excitation spectrum and topological characteristics of physical systems simply by adjusting the intensity, frequency, and polarization of light. Consequently, significant research effort has been devoted to the realization and manipulation of various long-pursued quantum states, such as Floquet Majorana fermions, new braiding protocols in the energy dimension, and chiral topology orders without equilibrium counterparts. For instance, the realization and control of Floquet states have been reported in both photon and cryogenic atomic systems. Another important area is condensed matter systems, where transient Floquet states have been primarily investigated.

[0005] However, due to the transient nature of pulsed lasers and the inherently short lifetime of the flocket state, the flocket state does not persist for longer than picoseconds. This short duration makes it difficult to fully investigate, understand, and utilize the new light-driven state in practical applications.

[0007] Another significant issue affecting most experimental implementations of flocket states is heating caused by energy absorption from periodic driving. Although various methods have been proposed to reduce or avoid heating effects, the heating problem persists because photon and cryogenic gas systems are well isolated from the external environment. In contrast, condensed matter systems possess defined electron cooling pathways, such as electron-phonon coupling and Wiedemann-Franz cooling of conductive electrons. However, the large electric fields in the optical domain used in previous condensed matter experiments necessitate pulsed measurements to avoid heating issues. One strategy to avoid thermal problems is to use low-frequency driving, which requires smaller electric fields. While experimental studies have been conducted in the microwave domain, they have relied on indirect methods to investigate flocket states by tracking time evolution, qubit resonator resonance conditions, magnetic resonance conditions, or alternating Josephson effects. Since the spacing between flocket states decreases proportionally with the use of lower frequency light, spectroscopy with high energy resolution is required to directly measure flocket states using low-frequency microwaves. Prior art literature

[0009] United States Patent Publication US2021 / 0242391 (September 5, 2021) The problem to be solved

[0010] Embodiments of the present invention are intended to provide a tunneling spectroscopy apparatus through the edge of a two-dimensional material for performing tunneling spectroscopy on a two-dimensional material such as graphene.

[0011] In addition, embodiments of the present invention are intended to provide a tunneling spectroscopy device through the edge of a two-dimensional material that can increase the energy resolution of tunneling spectroscopy.

[0012] In addition, embodiments of the present invention are intended to provide a tunneling spectroscopic device through the edge of a two-dimensional material for direct confirmation of the Floquet-Andreev state by the Andreev confinement state. means of solving the problem

[0014] According to one embodiment of the present invention, a tunneling spectroscopy apparatus through the edge of a two-dimensional material to be spectroscopically analyzed is provided, comprising: a tunneling probe that forms a tunneling junction in contact with the two-dimensional material and a spectrometer that analyzes physical property data detected through the tunneling probe; wherein the tunneling probe contacts the edge of the two-dimensional material.

[0016] The above two-dimensional material may be selected from graphene, transition-metal dichalcogenides, topological insulators, and topological semimetals.

[0017] The above tunneling probe can be formed of a superconductor.

[0018] The above superconductor may be selected from aluminum (Al), niobium (Nb), niobium nitride (NbN), niobium titanium (NbTi), niobium titanium nitride (NbTiN), lead (Pb), indium (In), rhenium (Re), gallium (Ga), molybdenum (Mo), and tin (Sn).

[0019] The above tunneling probe can be formed of ordinary metal.

[0020] The above general metal can be selected from gold (Au), silver (Ag), and platinum (Pt).

[0021] The tunneling probe can directly contact the edge of the two-dimensional material.

[0022] It may be for measuring the Andreev bound state formed in the above two-dimensional material. Effects of the invention

[0024] According to an embodiment of the present invention, a tunneling spectroscopy device through the edge of a two-dimensional material is provided for performing tunneling spectroscopy on a two-dimensional material such as graphene.

[0025] And, according to an embodiment of the present invention, a tunneling spectroscopy device through the edge of a two-dimensional material capable of increasing the energy resolution of tunneling spectroscopy is provided.

[0026] In addition, according to an embodiment of the present invention, a tunneling spectroscopic device through the edge of a two-dimensional material is provided for direct confirmation of the Floquet-Andreev state by the Andreev confinement state. Brief explanation of the drawing

[0028] FIG. 1 is a drawing showing the state in which a probe of a tunneling spectroscopic device according to an embodiment of the present invention comes into contact with a two-dimensional material that is an object. FIG. 2 is a drawing showing an enlarged view of section A of FIG. 1. Figure 3 is a schematic diagram illustrating the tunneling process between a probe and a two-dimensional material. FIG. 4 is a graph showing the energy resolution of a probe according to an embodiment of the present invention. Figure 5 is a graph showing the electrostatic potential at the interface between graphene and aluminum. Specific details for implementing the invention

[0029] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, this is merely illustrative and the disclosed embodiments are not limited thereto.

[0030] In describing the embodiments, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions could unnecessarily obscure the essence of the disclosed embodiments. Furthermore, terms described below are defined in consideration of their functions in the disclosed embodiments, and these may vary depending on the intent or practice of the user or operator. Therefore, such definitions should be based on the content throughout this specification. Terms used in the detailed description are intended merely to describe the embodiments and should not be limiting. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as "include" or "comprise" are intended to refer to certain characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof other than those described.

[0032] FIG. 1 is a diagram showing the state in which a probe (110) of a tunneling spectroscopic device (100) according to one embodiment of the present invention comes into contact with a two-dimensional material (10) which is an object.

[0034] Referring to FIG. 1, a tunneling spectroscopy device (100) may be used to perform tunneling spectroscopy on a two-dimensional material (10). The two-dimensional material (10) may be a two-dimensional material that forms a Josephson junction, and through tunneling spectroscopy, an Andreev bound state generated by the Josephson junction can be identified. In this case, the two-dimensional material may be graphene. However, the application of the tunneling spectroscopy device is not limited to this, and any object to which the tunneling spectroscopy device is applied may be a two-dimensional material (10). Such two-dimensional materials (10) may include graphene, transition-metal dichalcogenides, topological insulators, and topological quasimetals.

[0036] In FIG. 1, the material (20) surrounding the two-dimensional material may be superconducting aluminum (Al). Accordingly, the electrodes (20a, 20b) formed as superconductors and the two-dimensional material (10) between them may form a Josephson junction.

[0038] A probe (110) of a tunnel spectroscopic device may come into contact with the edge of a two-dimensional material (10). The probe (110) may be a superconductor, specifically aluminum (Al), niobium (Nb), niobium nitride (NbN), niobium titanium (NbTi), niobium titanium nitride (NbTiN), lead (Pb), indium (In), rhenium (Re), gallium (Ga), molybdenum (Mo), tin (Sn), etc. The contact portion (110a) of the probe (110) may come into direct contact with the edge (10a in FIG. 2) of the two-dimensional material (10). A high-potential barrier for tunneling can be formed between the probe (110) and the two-dimensional material (10) by the contact portion (110a) of the probe (110) making direct contact with the edge (10a) of the two-dimensional material (10). This may be because there is a large interatomic distance between the atoms of the two-dimensional material (10) and the atoms of the probe (100). A similar technique can also be used to form tunnel contacts between a multi-walled carbon nanotube and a metal electrode.

[0040] The probe (110) is preferably a superconductor, but is not limited thereto and can be formed from a general metal. Such general metals may include gold (Au), silver (Ag), platinum (Pt), etc.

[0042] By applying a bias current (I) between the probe (110) and the two-dimensional material (10), the voltage difference (V) between them can be measured. Through this, the tunneling differential conductance (dI / dV) can be obtained, which can represent the convolution of the density of state function of the Andreev confined state in the Josephson junction and the density of state function of the probe (110).

[0044] The tunneling spectroscopic device (100) may include, in addition to the probe (110) described above, a spectrometer (120) for performing tunneling spectroscopic analysis and a control unit (130) for controlling the overall operation of the spectroscopic device (100). The remaining components other than the probe (110) may be similar to the components used in a known tunneling spectroscopic device (100).

[0046] Figure 2 is a drawing showing an enlarged view of part A of Figure 1.

[0048] Referring to FIG. 2, the contact portion (110a) of the probe (110) may come into direct contact with the edge (10a) of the two-dimensional material (10). The edge (10a) of the two-dimensional material (10) may refer to the outer portion of the two-dimensional material (10) that is not the part corresponding to the plane (10a). By the contact portion (110a) of the probe (110) coming into direct contact with the edge (10a) of the two-dimensional material (10), tunneling as described in FIG. 3 may occur.

[0050] FIG. 3 is a schematic diagram showing the tunneling process between the probe (110) and the two-dimensional material (10).

[0052] Referring to FIG. 3, the density of states function peak of the probe (110) and the bias voltage V (V=Δ Al +E + It can be confirmed that ) / e) match each other. Here, Δ Al This may correspond to the superconducting gap of the probe (110). The density of states function peak of the probe (110) indicates that it provides high energy resolution in a tunneling spectroscopic device. Thus, the bonding method between the probe (110) and the two-dimensional material (10) according to one embodiment of the present invention can provide high energy resolution in a tunneling spectroscopic device.

[0054] FIG. 4 is a graph showing the energy resolution of a probe (110) according to one embodiment of the present invention.

[0056] Referring to FIG. 4, the graph is for the case where the microwave power (P) is -5.2 dBm. In FIG. 4(a), the blue line represents the raw data of the tunneling differential conductance (dI / dV) measured by the probe (110), and the red line represents the background value. FIG. 4(b) shows the difference between the raw data (blue line) and the background value (red line) in FIG. 4(a). In the graph of FIG. 4(b), it can be seen that the full width half maximum (the width indicated by the arrow in FIG. 4(b)), which represents the width at half the peak, is 22 μeV, and this corresponds to the energy resolution. Therefore, in the case of the probe (110) according to one embodiment of the present invention, particularly when the probe (110) is formed of a superconductor, it can be seen that the energy resolution is improved and precise spectroscopy can be performed.

[0058] Figure 5 is a graph showing the electrostatic potential at the interface between graphene and aluminum.

[0060] Referring to Fig. 5, when examining the electrostatic potential according to the arrangement of graphene (yellow) and aluminum (purple), a potential barrier (B) appears at the interface between graphene and aluminum. Due to this potential barrier (B), tunneling occurs between graphene and aluminum, and it can be indicated that a tunneling junction occurs between graphene and aluminum.

[0062] Although representative embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications can be made to the above-described embodiments without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof. Explanation of the symbols

[0064] 10 : 2D material 20 : Superconductor 100: Tunneling Spectrometer 110 : Probe 110a : Contact part 120 : Spectrometer 130 : Control unit

Claims

Claim 1 A tunneling spectroscopy apparatus through the edge of a two-dimensional material to be spectroscopically analyzed comprises: a tunneling probe that forms a tunneling junction in contact with the two-dimensional material and a spectrometer that analyzes physical property data detected through the tunneling probe; wherein the tunneling probe contacts the edge of the two-dimensional material. Claim 2 A tunneling spectrometer through the edge of a two-dimensional material according to claim 1, wherein the two-dimensional material is selected from graphene, transition-metal dichalcogenides, topological insulators and topological semimetals. Claim 3 The tunneling probe of claim 1 is a tunneling spectroscopic device through the edge of a two-dimensional material formed of a superconductor. Claim 4 In claim 3, the superconductor is a tunneling spectroscopic device through the edge of a two-dimensional material selected from aluminum (Al), niobium (Nb), niobium nitride (NbN), niobium titanium (NbTi), niobium titanium nitride (NbTiN), lead (Pb), indium (In), rhenium (Re), gallium (Ga), molybdenum (Mo), and tin (Sn). Claim 5 The tunneling probe of claim 1 is a tunneling spectroscopic device through the edge of a two-dimensional material, formed of a general metal. Claim 6 A tunneling spectrometer through the edge of a two-dimensional material according to claim 5, wherein the general metal is selected from gold (Au), silver (Ag), and platinum (Pt). Claim 7 A tunneling spectroscopic device through the edge of a two-dimensional material, wherein the tunneling probe is in direct contact with the edge of the two-dimensional material. Claim 8 The tunneling spectroscopic apparatus through the edge of a two-dimensional material for measuring an Andreev bound state formed in the two-dimensional material according to claim 1.

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