Topological Crystalline Superconductivity in Dirac Semimetal Phase of Iron-based Superconductors

Recently, topological states of iron-based superconductors have attracted much attention. In Fe(Se, Te) and LiFeAs, triple band inversions occur between a p_z orbital and three d orbitals [1,2]. ARPES experiments showed that one of the inversions near the Fermi level forms topological insulating gap [1]. Furthermore, another inversion at higher energy causes a band touch with linear dispersion [2]. Therefore, these systems with carrier doping can be Dirac semimetal.
Motivated by these experiments, we theoretically investigated unconventional superconductivity of this Dirac semimetal in iron-based superconductors [3]. We found that the Cooper pair between the electrons with d- and p-orbitals in this system yields odd-parity superconductivity. In the presentation we will discuss its topological property and typical surface states, such as Majorana flat band, Majorana quartet, and Möbius twisted surface states.

[1] P. Zhang, et al., Science 360, 182 (2018).
[2] P. Zhang, et al., Nat. Phys. 15, 41 (2019).
[3] T. Kawakami and M. Sato, Phys. Rev. B 100, 094520 (2019).