湛江海滨公园Rearch Progress of Two-dimensional Superconducting Materials
Jiawei Li
School of Physics, East China University of Science and Technology, Shanghai,200237,P.R.China
Abstract: Superconducting materials refer to a certain low temperature under the condition of showing the resistance is equal to zero properties of materials. Superconducting materials were first discovered in 1911 by the Dutch physicist Kemelin Onnes. After more than 100 years of rearch and development, about 28 elements and thousands of alloys and compounds have been found to have superconductivity. Among the materials, two-dimensional materials have very good properties and properties, so how to realize the superconductivity in two-dimensional materials has gradually become the direction of physicists' efforts to study. In recent years, many two-dimensional materials such as graphene and MoS2 have been reported to have superconductivity.[1] This paper will review the rearch history of two-dimensional superconductivity materials in the past decades, introduce veral two-dimensional materials with great rearch potential, and finally make prospects for the rearch of two-dimensional superconductivity materials.
Keywords: Two-dimensional materials;Superconductivity;Graphene;Borophene;P hosphorene
DOI: 10.47297/taposatWSP2633-456922.20220302
亮剑精神1. Rearch History of Two-dimensional Superconducting Materials
In 1934, C. J. Gorter and H. B. G. Casimir propod the two-fluid model of superconducting state, and believed that the superconducting state was more ordered than normal state becau of some ordered changes in common electrons (band theory).[12] In 1935, two brothers, F. London and H. London, bad on the two-fluid model and Maxwell’s electromagnetic theory, propod the macroscopic electromagnetic theory of superconductor and successfully explained the zero resistance phenomenon and Meisner effect of superconductor.[13] In terms of
江苏会计网
About the author: Jiawei Li (1999-11), School of physics, East China University of Science and Technology, 200237. undergraduate, Rearch direction: physics.
Vol.3 No.2 2022
experiments, Shal’ Nikov first studied and reported the superconductivity of Pb and Sn films in 1938.[14] In 1950, V.L.Ginzburg and L.D.Landau propod the phenomenological theory of superconductivity (GL theory) bad on the theory of cond-order pha transition.[15] In 1957, J.B
ardeen, L.N.Cooper and J.R.Schrieffer established the microscopic theory of superconducting states, or BCS theory. And that’s the theory we still u today.[16]
塞班岛是哪个国家
Since the 21st century, due to the emergence of advanced experimental equipment and a large number of breakthroughs in material preparation technology, such as molecular beam epitaxial growth method, mechanical stripping method, chemical vapor deposition method and other low-dimensional materials preparation methods, the quality of two-dimensional superconducting materials prepared by laboratory has been greatly improved. The basic materials ud in the study of the superconductivity of two-dimensional materials are as follows: graphene, borophene, phosphorene, and transition metal chalcogenides. Due to the intrinsic miconductor properties of the materials, most of them require various controls to make them superconductive. Common control methods include chemisorption, stress and carrier doping.[1]
2. Two-dimensional Materials with Rearch Potential
(1) Graphene Graphene is the first two-dimensional material discovered. It is a two-dimensional material with a single hexagonal honeycomb lattice structure made of carbon atoms linked by sp2 hybrid orbitals. The electron-phonon coupling strength in graphene can be effectively adjusted by strain and charge doping, which can
improve the transition temperature of two-dimensional superconducting materials.
Fig.1 Schematic diagram of graphene lattice structure [17]
1) Preparation of graphene Ever since graphene was discovered, it has been made by stripping it with tape. In recent years, many other methods have emerged to produce graphene in large quantities. Liquid pha exfoliation (LPE) is also one of the most commonly ud methods for large-scale production of graphene. The process can be divided
Theory and Practice of Science and Technology
into three stages: firstly, the raw material of graphene flakes is broken by ultrasonic oscillation, and den stripes are formed on the surface of the fragments. Secondly, cracks are created along the streaks. Thirdly, organic solvents are added to make the flakes flake to form graphene.[2] Supercritical fluid spalling (SCF) is a new and promising method. The graphite is first immerd in a supercritical fluid, which has a high diffusion efficiency, so the graphite is intercalated by the supercritical fluid. When the pressure is relead, the supercritical fluid expands rapidly, thus layering the graphene.[9] Chemical vapor deposition (CVD) is also ud to produce graphene. It has the advantages of mass preparation, high quality and controllable graphene layers. Its principle is to u one or veral gas pha compounds or elemental elements containing film, on the surface of the substrate chemical reaction to generate film.[2]
2) Superconductivity of graphene
The usual way to make graphene superconducting is to attach alkali metals to the graphene. In IchinokuraS's experiment, we found 4K superconductivity in the Ca intercalated bilayer graphene (C6 CaC6), but not in the Li intercalated bilayer graphene (C6 LiC6), which proves the important role of some elements in regulating superconductivity of graphene. However, there are not enough experimental data to prove the superconductivity regulated by stress and carrier.[1] In the MIT Pablo
Jarillo-Herrero group's experiments, a type of torsional graphene was also found to be superconductive. Superconductivity occurs when the Angle of the double-layer graphene approaches the magic Angle (It is 1.1° under normal conditions).[10]
作业一Fig. 2 (a) Electric transport curves of Li and Ca intercalated bilayer graphene, where Ca intercalated bilayer graphene exhibits superconductivity but Li intercalated bilayer graphene does not; (b) Diamagnetic signal displayed by Ca intercalated bilayer graphene [1]
(2) Phosphorene
Phosphorene, also known as black phosphorene or two-dimensional black phosphorus, is a two-dimensional miconductor material compod of ordered phosphorus atoms stripped from black phosphorus, single atomic layer, and a direct band gap. Black phosphorus has four crystal structures: orthogonal, rhombus,
Vol.3 No.2 2022 simple cubic and amorphous.[4]
1) Preparation of phosphorene
The commonly ud methods are mechanical stripping and liquid stripping. Similar to graphene, blac
泊怎么读音
k phosphorus has weak interlayer van der Waals force, which can be easily removed mechanically, and the number of layers removed can be effectively controlled by plasma thinning. Due to the low yield of mechanical stripping method and the quality of finished products cannot be controlled, more liquid pha stripping method is ud. Brent's rearch group obtained black phosphorus with a thickness of 3.5-5nm and a large surface area through this method. In addition, black phosphorus has also been prepared by puld lar deposition (PLD).[2,4]
2) Superconductivity of phosphorene
Becau of the characteristics of phosphorene miconductor, it must be regulated to achieve superconductivity. On the theoretical side, a great deal of work has predicted that the electron doping method can make black phosphorus superconductive at a concentration of 1.3×1014 cm-2. If this concentration is incread to 2.6×1014 cm-2, T c can be incread above liquid helium.[1] In the experiment, Li, Rb, Cs and Ca metals can be intercalated in black phosphorus by liquid nitrogen intercalation technology, and the superconductivity of black phosphorus can be made independent of the type of intercalated atoms.[8]
(3) Borophene
Boron and nitrogen, as the two elements adjacent to carbon, are also most likely to be two-dimensional materials. After a long period of rearch, people found a two-dimensional material hexagonal boron nitrite (h-BN) with honeycomb structure, and two-dimensional boron with plane structure is borophene, borophene is a two-dimensional allotrope of boron element.[5]
Fig. 3 (a) the structure of B12 Icosahedral; (b) the structure of rhombic boron; (c) the structure of
ScB12; (d) the structure of B4C [5]
Theory and Practice of Science and Technology
1) Preparation of borophene
In terms of theoretical calculation, it has been calculated that the monolayer lattice clusters with warping triangle of B42 and B46 can exist stably. Later, it was calculated that a single layer of boron with a warped triangular lattice could exist stably. Until 2010, Gao Hongjun's rearch group from the Institute of Physics, Chine Academy of Sciences prepared multi-walled boron nanotubes with a diameter of 10-40nm by chemical vapor deposition method, which confirmed the preparation of borophene from the experimental direction. In 2015, Peng Cheng and his team from the Institute of
Physics, Chine Academy of Sciences prepared monolayer borylene with Ag (111) as the substrate by ultra-vacuum molecular beam epitaxy.[5]
思想汇报模板2) Superconductivity of borophene
The reason why borophene is considered to have superconductivity by many rearchers is that MgB2, a compound of boron, is a superconducting material with good performance, and its superconducting transition temperature can reach 39K. However, for simple borylene, there is no experimental proof of its superconductivity, only theoretical inference. A number of theoretical studies have shown that borophene may exhibit superconductivity in the temperature range of 10-20K. [1,5]
(4) Transition metal disulfide compounds (TMDs)
TMDs materials are two-dimensional materials with general formula MX2, where X reprents chorionic elements and M reprents transition metal atoms of groups 4-10. The morphology is similar to that of graphite. The transition metal atoms are hexagonal, and there are chorionic atoms alternately between the transition metal layers. The most reprentative is MoS2.[2,3]十大必看玄幻小说
1) Preparation of transition metal disulfide compounds (taking MoS2 as an example)
Becau MoS2 has a layered structure very similar to graphene, layered MoS2 flakes can be easily obtained by mechanical stripping. There is also a liquid stripping method (LE).[2] In 2016, Zhang's rearch group ud Li to carry out electrochemical discharge, and inrted Li into MoS2 during this process, while conducting ultrasonic oscillation, and finally obtained monolayer MoS2 of high quality, which can be prepared on a large scale.[11] MoS2 can also be prepared by chemical vapor deposition (CVD). High temperature annealing is most commonly ud now. MoS2 prepared by this method has good properties and controllable size and number of layers.
2) Superconductivity of transition metal disulfide compounds (taking MoS2 as an example)
MoS2 with many layers is an indirect band gap miconductor, but the band
