Sun Yue, Kittaka Shunichiro, Sakakibara Toshiro, Machida Kazushige, Wang Jinghui, Wen Jinsheng, Xing Xiangzhuo, Shi Zhixiang, Tamegai Tsuyoshi
Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258, Japan.
Phys Rev Lett. 2019 Jul 12;123(2):027002. doi: 10.1103/PhysRevLett.123.027002.
In the electronic nematic state, an electronic system has a lower symmetry than the crystal structure of the same system. Electronic nematic states have been observed in various unconventional superconductors such as cuprate, iron-based, heavy-fermion, and topological superconductors. The relation between nematicity and superconductivity is a major unsolved problem in condensed matter physics. By angle-resolved specific heat measurements, we report bulk quasiparticle evidence of nematicity in the topological superconductor Sr_{x}Bi_{2}Se_{3}. The specific heat exhibited a clear twofold symmetry despite the threefold symmetric lattice. Most importantly, the twofold symmetry appeared in the normal state above the superconducting transition temperature. This is explained by the angle-dependent Zeeman effect due to the anisotropic density of states in the nematic phase. Such results highlight the interrelation between nematicity and unconventional superconductivity.
在电子向列相中，电子系统的对称性低于同一系统的晶体结构。在各种非常规超导体中，如铜酸盐、铁基、重费米子和拓扑超导体中，都观察到了电子向列相。向列性与超导性之间的关系是凝聚态物理中一个尚未解决的主要问题。通过角分辨比热测量，我们报告了拓扑超导体Sr_{x}Bi_{2}Se_{3}中向列性的体准粒子证据。尽管晶格具有三重对称性，但比热表现出明显的二重对称性。最重要的是，这种二重对称性出现在超导转变温度以上的正常态中。这可以用向列相中态密度的各向异性导致的角度相关塞曼效应来解释。这些结果突出了向列性与非常规超导性之间的相互关系。
