Topological Superconductivity and Density Waves on the surface of Topological Kondo Insulator

We study the weak-coupling instabilities in the particle-particle and particle-hole channels on the surface of a prototype Kondo topological insulator. We draw inspiration from samarium hexaboride (SmB6), and the possible observation of its correlation physics through magnetoresistance hysteresis[1]. We work on the 100-surface, which has square C4v symmetry and contains three Dirac cones (electron or hole pockets) at Γ and two X points in momentum space. For superconducting order, we find phases supporting non-zero magnetization and spin current in the ground state, with certain symmetries broken by the condensates of inter-pocket order parameters. The intra-pocket pairings in general lead to a non-zero Chern number in Bogoliubov band, hinting topological superconductivity and the presence of Majorana zero modes bounded to defects. For exciton pairings, similar symmetry breaking phases are discovered.

[1]Nakajima, Y., Syers, P., Wang, X., Wang, R. and Paglione, J., 2016. One-dimensional edge state transport in a topological Kondo insulator. Nature Physics, 12 (3), p.213.