Andreev reflection in monolayer MoS2

Andreev reflection in a monolayer molybdenum disulfide superconducting-normal (S/N) hybrid junction is investigated. We find, by using a modified-Dirac Hamiltonian and the scattering formalism, that the perfect Andreev reflection happens at normal incidence with $p$-doped S and N regions. The probability of the Andreev reflection and the resulting Andreev conductance, in this system, are demonstrated to be large in comparison with corresponding gapped graphene structure. We further investigate the effect of a topological term ($\beta)$ in the Hamiltonian and show that it results in an enhancement of the Andreev conductance with $p$-doped S and N regions, while in the corresponding structure with $n$-doped S region it is strongly reducible in comparison. This effect can be explained in terms of the dependence of the Andreev reflection probability on the sign of $\beta$ and the chemical potential in the superconducting region.