Exploring the effects of Spin Orbit Coupling on the interplay of topology and superconductivity in CaBi2

A new group of materials have recently been identified displaying both superconductivity and topological insulating behaviour, which are of interest in the field of quantum computing. The interplay between superconductivity and topology has yet to be established, making a promising new avenue for research.CaBi2 is proposed to be such a material, with a superconducting transition at 1.95K. Extensive first principles calculations have highlighted the importance of the degree of spin orbit coupling involved to the phonon dispersion and electron-phonon coupling driving the superconductivity. We propose to clarify the significance of it by mapping out the single crystal phonon dispersion, looking at the in-plane Bi modes that are predicted to show a Kohn anomaly in the absence of strong spin orbit coupling.

近期研究人员发现了一类兼具超导性与拓扑绝缘性的新型材料体系，此类材料在量子计算领域具有重要研究价值。超导性与拓扑特性之间的相互作用机制尚未阐明，这为相关研究开辟了极具潜力的全新方向。CaBi2被认为是这类材料之一，其超导转变温度为1.95开尔文。大量第一性原理计算（first principles calculations）已表明，自旋轨道耦合（spin orbit coupling）的强度对声子色散以及驱动超导的电子-声子耦合过程均具有关键影响。本研究拟通过绘制单晶声子色散谱，重点考察在无强自旋轨道耦合条件下理论预测会出现科恩反常（Kohn anomaly）的面内铋振动模式，以此阐明自旋轨道耦合的关键意义。