基于BiS的层状超导体中由结构对称性破缺驱动的可能的配对机制转变。

Possible pairing mechanism switching driven by structural symmetry breaking in BiS-based layered superconductors.

作者信息

Yamashita Aichi, Usui Hidetomo, Hoshi Kazuhisa, Goto Yosuke, Kuroki Kazuhiko, Mizuguchi Yoshikazu

机构信息

Department of Physics, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, 192-0397, Japan.

Department of Physics and Materials Science, Shimane University, 1060, Nishikawatsucho, Matsue, 690-8504, Japan.

出版信息

Sci Rep. 2021 Jan 19;11(1):230. doi: 10.1038/s41598-020-80544-2.

DOI:10.1038/s41598-020-80544-2

PMID:33469088

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC7815720/

Abstract

Investigation of isotope effects on superconducting transition temperature (T) is one of the useful methods to examine whether electron-phonon interaction is essential for pairing mechanisms. The layered BiCh-based (Ch: S, Se) superconductor family is a candidate for unconventional superconductors, because unconventional isotope effects have previously been observed in La(O,F)BiSSe and BiOS. In this study, we investigated the isotope effects of S and S in the high-pressure phase of (Sr,La)FBiS, which has a monoclinic crystal structure and a higher T of ~ 10 K under high pressures, and observed conventional-type isotope shifts in T. The conventional-type isotope effects in the monoclinic phase of (Sr,La)FBiS are different from the unconventional isotope effects observed in La(O,F)BiSSe and BiOS, which have a tetragonal structure. The obtained results suggest that the pairing mechanisms of BiCh-based superconductors could be switched by a structural-symmetry change in the superconducting layers induced by pressure effects.

摘要

研究同位素对超导转变温度（T）的影响是检验电子 - 声子相互作用对于配对机制是否至关重要的有用方法之一。基于层状BiCh（Ch：S，Se）的超导体家族是非常规超导体的候选者，因为先前在La（O，F）BiSSe和BiOS中观察到了非常规同位素效应。在本研究中，我们研究了具有单斜晶体结构且在高压下具有约10 K的较高T的（Sr，La）FBiS高压相中的S和S的同位素效应，并观察到T中的常规类型同位素位移。（Sr，La）FBiS单斜相中的常规类型同位素效应不同于在具有四方结构的La（O，F）BiSSe和BiOS中观察到的非常规同位素效应。所得结果表明，基于BiCh的超导体的配对机制可能会因压力效应引起的超导层结构对称性变化而发生切换。