Identify the Chiral Superconductivity in 4Hb-TaS2 through Magnetic-Spectral Responses

Chiral superconductivity, which breaks time-reversal symmetry spontaneously, is an alternative ingredient to cook up a topological superconductor holding the Majorana fermions that can be used to perform fault-tolerant quantum computation. A recent experiment [1] showed signatures of time-reversal symmetry breaking in superconducting 4Hb-TaS2 which abruptly appeared at the critical temperature Tc, implying possibility for the existence of chiral superconductivity. Through group theory analysis, we argue that only a chiral and a non-chiral superconducting states are allowed by the crystalline symmetry and strong Ising-type spin-orbital coupling in 4Hb-TaS2, both of which are mixed singlet-triplet states. It is further shown that the non-chiral superconducting state is more susceptible to an in-plane magnetic field and can be magnetically driven to a nodal superconducting phase, while the chiral one does not share this property. According to their different magnetic-spectral responses, an experimentally feasible way concerning the measurement of specific heat is proposed to identify the chiral superconductivity from the non-chiral one for this particular material.

[1] A. Ribak. et al. arXiv:1905.02225 (2019)