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Pressure-induced topological superconductivity in the spin–orbit Mott insulator GaTa 4 Se 8
npj Quantum Materials ( IF 5.7 ) Pub Date : 2020-06-24 , DOI: 10.1038/s41535-020-0246-0
Moon Jip Park , GiBaik Sim , Min Yong Jeong , Archana Mishra , Myung Joon Han , SungBin Lee

Lacunar spinel GaTa4Se8 is a unique example of spin–orbit coupled Mott insulator described by molecular jeff = 3/2 states. It becomes superconducting at Tc = 5.8 K under pressure without doping. In this work, we show, this pressure-induced superconductivity is a realization of a new type topological phase characterized by spin-2 Cooper pairs. Starting from first-principles density functional calculations and random phase approximation, we construct the microscopic model and perform the detailed analysis. Applying pressure is found to trigger the virtual interband tunneling processes assisted by strong Hund coupling, thereby stabilizing a particular d-wave quintet channel. Furthermore, we show that its Bogoliubov quasiparticles and their surface states exhibit novel topological nature. To verify our theory, we propose unique experimental signatures that can be measured by Josephson junction transport and scanning tunneling microscope. Our findings open up new directions searching for exotic superconductivity in spin–orbit coupled materials.



中文翻译:

自旋轨道Mott绝缘子GaTa 4 Se 8中压力诱导的拓扑超导

腔尖晶石GaTa 4 Se 8是用分子j eff  = 3/2状态描述的自旋轨道耦合Mott绝缘子的独特示例。 在不掺杂的情况下,它在T c = 5.8 K的条件下变为超导。在这项工作中,我们表明,这种压力诱导的超导性是一种以spin-2 Cooper对为特征的新型拓扑相的实现。从第一原理密度泛函计算和随机相位近似开始,我们构建微观模型并进行详细分析。发现施加压力可触发强大的Hund耦合辅助的虚拟带间隧穿过程,从而稳定特定的d五重奏通道。此外,我们表明其Bogoliubov准粒子及其表面状态表现出新颖的拓扑性质。为了验证我们的理论,我们提出了可以通过约瑟夫森结传输和扫描隧道显微镜测量的独特实验签名。我们的发现为寻找自旋轨道耦合材料中的超导性开辟了新的方向。

更新日期:2020-06-24
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