锶钌酸盐中令人困惑的超导性：过去与现在
Puzzling superconductivity in strontium ruthenate: then and now
中文总结 AI 辅助
本文聚焦锶钌酸盐超导性，回顾其研究进展，针对其可能是自旋单重态超导体的情况，计算一种候选d波配对态的克尔效应，通过两个求和规则表征霍尔电导，发现计算结果与此前有关手性p波假设下的结果定性相似。
中文摘要 AI 辅助
锶钌酸盐是一种非常有趣的低温超导体，其正常态相对简单，超导态性质却极为令人困惑。尽管经过三十多年的深入研究，序参量的精确对称性仍未知。本文简要回顾一些关键进展，聚焦较新实验，尤其是那些挑战其为自旋三重态奇宇称手性p波超导体这一先前认知的实验。鉴于Sr₂RuO₄现在很可能是自旋单重态超导体，我们计算了一种候选d波配对态的克尔效应。发现对于手性d波Eg配对态，计算出的霍尔电导非零，且定性上与早期在手性p波Eu序参量假设下发现的相似。我们根据两个求和规则来表征霍尔电导，一个与博戈留波夫准粒子态中的贝里曲率有关，另一个f求和规则表明存在轨道间配对。
英文摘要
Strontium ruthenate is a very interesting low temperature superconductor with relatively simple normal state and very puzzling superconducting state properties. Despite over thirty years of intensive research, even the precise symmetry of the order parameter is not known. In this paper we briefly review some of the key developments, focussing on some of the newer experiments, especially those which challenged the previous understanding that it is a spin triplet odd parity chiral p-wave superconductor. Since Sr$_2$RuO$_4$ now appears most probably a spin singlet superconductor we have calculated the Kerr effect for one candidate $d$-wave pairing state. We find that for the chiral $d$-wave $E_g$ pairing state the calculated Hall conductance is non-zero and qualitatively similar to that found earlier under the assumption of a chiral p-wave $E_u$ order parameter. We characterize the Hall conductance in relation to two sum rules, one related to Berry curvatures in the Bogoliubov quasiparticle states, and the other $f$-sum rule indicating the presence of inter-orbital pairing.
