拓扑材料中的超导

近来,人们在凝聚态体系中发现了由拓扑不变量定义的物相,其中最重要的有拓扑绝缘体、拓扑半金属和拓扑超导体等.这些物相的拓扑性质由非平凡的拓扑数描述,相应的材料被称为拓扑材料,具有诸多新奇的物理特性.其中拓扑超导体由于边界上有满足非阿贝尔统计的Majorana零能模,成为实现拓扑量子计算的主要候选材料.除了探索本征的拓扑超导体外,由于拓扑性质上的相似性,在不超导的拓扑材料中调制出超导自然成为了实现拓扑超导的重要手段.目前,人们发展了栅极调制、掺杂、高压、近邻效应调制和硬针尖点接触等多种技术,已经成功地在许多拓扑绝缘体和半金属中诱导出了超导,并对超导的拓扑性和Majorana零能模进行了研究.本文回顾了本征拓扑超导候选材料,以及拓扑绝缘体和半金属中诱导出超导的代表性工作,评述了不同实验手段的优势和缺陷、分析了其超导拓扑性的证据,并提出展望.

Superconductivity in topological

In recent years, by introducing topological invariants into condensed matter systems, new phases of mater are revealed. Of these new phases, the topological insulator, topological semimetal and topological superconductor are the most important. They are called topological materials due to nontrivial topological parameters. Topological superconductors hold Majorana zero modes at the edges, satisfying non-abelian statistics, which makes them major candidate for realizing topological quantum computation. Besides exploring intrinsic topological superconductor, a promising way to realize topological superconductor is to induce superconductivity into other kinds of topological materials. Up to now, experimentalists have developed some techniques, such as gating, doping, high pressure, interface effect and hard point contact to introduce superconductivity into various topological materials, and also they have studied the topological properties of the induced superconductivity. In this review, we summarize the representative researches on intrinsic topological superconductor candidates and induced superconductivities in topological insulators and semimetals. The advantages and disadvantages of different techniques are discussed. Besides, the potential evidences of topological superconductors are analyzed. In the end, the outlook of this actively pursued research field is given.