Pressure-induced topological superconductivity in the spin–orbit Mott insulator GaTa4Se8

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...

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Bibliographic Details
Published in:npj quantum materials 2020-06, Vol.5 (1), Article 41
Main Authors: Park, Moon Jip, Sim GiBaik, Jeong, Min Yong, Mishra Archana, Han, Myung Joon, Lee, SungBin
Format: Article
Language:English
Subjects:
Cooper pairs
Coupling (molecular)
Elementary excitations
First principles
Josephson junctions
Superconductivity
Topology
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Summary: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.
ISSN:2397-4648
2397-4648
DOI:10.1038/s41535-020-0246-0