Electric field modulated valley- and spin-dependent electron retroreflection and Klein tunneling in a tilted n−p−n junction of monolayer 1T′−MoS2

We study the electronic transport properties in a tilted $n\text{\ensuremath{-}}p\text{\ensuremath{-}}n$ junction of monolayer $1{T}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{MoS}}_{2}$ under a vertical electric field. The analytical derivations and numerical results show that, since the spin degeneracy of the anisotropic bands of monolayer $1{T}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{MoS}}_{2}$ is lifted by the electric field ${E}_{z}$, electrically tunable valley- and spin-dependent electron retroreflection occurs in the tilted $n\text{\ensuremath{-}}p\text{\ensuremath{-}}n$ junction. It is also found that when the electric field ${E}_{z}$ is adjusted to a critical value ${E}_{c}$, valley- and spin-dependent Klein tunneling happens in the $n\text{\ensuremath{-}}p\text{\ensuremath{-}}n$ junction, and the incident angle of Klein tunneling depends on the tilt angle of the junction. Especially, for a certain specific tilt angle, in the case of normal incidence, only a spin-up electron from the $K$ valley can undergo Klein tunneling. Our work offers an efficient mechanism to modulate valley- and spin-dependent electron retroreflection and Klein tunneling in anisotropic tilted Dirac systems.