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-p-n junction of monolayer 1T'-MoS2 under a vertical electric field. The analytical derivations and numerical results show that, since the spin degeneracy of the anisotropic bands of monolayer 1T'-MoS2 is lifted by the electric field E-z, electrically tunable valley-and spin-dependent electron retroreflection occurs in the tilted n-p-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-p-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.