Transport properties of spin-triplet superconducting monolayer $MoS_2$

Abstract

The quantum transport properties of graphene and monolayer $MoS_2$ superconductor heterostructures has been of considerable importance in the recent few years. Layered nature of molybdenum disulfide permits the superconducting correlation induction. Moreover, peculiar dynamical features of monolayer $MoS_2$, such as valence band spin-splitting in the nondegenerate $K$ and $K'$ valleys originated from strong spin-orbit coupling, and considerable direct band gap can make it potentially a useful material for electronics applications. Using the Dirac-like Hamiltonian of $MoS_2$ with taking into account the related mass asymmetry and topological contributions, we investigate the effect of spin-triplet $p$-wave pairing symmetry on the superconducting excitations, resulting in Andreev reflection process and Andreev bound state in the corresponding normal-superconductor (NS) and superconductor-normal-superconductor (SNS) structures, respectively. We study how the resulting subgap conductance and Josephson current are affected by the particular symmetry of order parameter. The signature of $p_x$-wave symmetry is found to decline the subgap superconducting energy excitations and, consequently, slightly suppress the Andreev reflection in the case of $p$-doped S region. The essential dynamical parameters $\lambda$ and $\beta$ of $MoS_2$ have significant effect on the both tunneling conductance and Josephson current. Particularly, the considered $p$-wave symmetry in the superconducting bound energies may feature the zero energy states at the interfaces. The critical current oscillations as a function of length of junction are obtained in the $p$-doped S region.