Exchange interaction as the source of topological superconductivity on the surface of FeTe0.5Se0.5

Chih-Kai Yang^1*

¹Graduate Institute of Applied Physics, National Chengchi University, Taipei, Taiwan

* Presenter:Chih-Kai Yang, email:ckyang@nccu.edu.tw

FeTe1-xSex is a family of iron-based superconductors with a well-known critical temperature of 14.5 K for x = 0.45. Also well-established is the presence of topological surface states of FeTe0.55Se0.45 in which topological superconductivity sets in. By using density functional calculations and the Bardeen-Cooper-Schrieffer (BCS) theory for traditional superconductors we calculated the critical temperature of the surface layers of FeTe0.5Se0.5 with the exchange interaction as the source of attractive interaction to form the Cooper pairs. The calculated critical temperature is in reasonable agreement with the experimental value and suggests that the exchange interaction is behind the topological superconductivity on the surface of FeTe0.55Se0.45 and perhaps beyond.

Keywords: Topological superconductivity, Iron-based superconductor, Pairing mechanism