Gate-controlled valley transport and Goos–Hänchen effect in monolayer WS₂

Abstract

Based on a Dirac-like Hamiltonian and coherent scattering formalism, we study the spin-valley transport and Goos-Hänchen-like (GHL) effect of transmitted and reflected electrons in a gated monolayer WS. Our results show that the lateral shift of spin-polarized electrons is strongly dependent on the width of the gated region and can be positive or negative in both Klein tunneling and classical motion regimes. The absolute values of the lateral displacements at resonance positions can be considerably enhanced when the incident angle of electrons is close to the critical angle. In contrast to the time reversal symmetry for the transmitted electrons, the GHL shift of the reflected beams is not invariant under simultaneous interchange of spins and valleys, indicating the lack of spin-valley symmetry induced by the tunable potential barrier on the WS monolayer. Our findings provide evidence for electrical control of valley filtering and valley beam splitting by tuning the incident angle of electrons in nanoelectronic devices based on monolayer transition metal dichalcogenides.

Band-offset-induced lateral shift of valley electrons in ferromagnetic MoS2/WS2 planar heterojunctions

“…Similar results have also been reported in the GHL shift of electron beam transmitted through a ferromagnetic silicene [44]. Moreover, in our recent work [40], GHL shift of both transmitted and reflected electrons in a gated monolayer WS 2 was studied. Interestingly, it was shown that in contrast to the transmitted beam, the GHL shift of reflected electrons is not invariant under simultaneous interchange of spin and valley indexes.…”

“…In the vicinity of resonance positions the lateral shift can be greatly enhanced (see Refs. [32,40]). At resonance positions which are determined by the condition k 2x d = nπ, (n = 1, 2, 3, ....), the heterojunction becomes transparent (T = 1) and σ τ tr,sz acquires local maxima which are obtained from σ τ tr,sz k2xd=nπ =…”

“…The total reflection can lead to electron confinement in region 2 between the two interfaces associated with multiple reflections from the interfaces at x = 0 and x = d. Furthermore, based on the stationary phase method [40], the GH lateral shift of the reflected beam can be obtained as…”

Electron scattering in a superlattice of line defects on the surface of topological insulators

“…Interestingly, we can see in Fig. 8(a)-(b) perfect transmissions for normally incident electrons (θ = 0), regardless of the potential strengths and the number of ripples in y direction, which is a typical signature of Klein tunneling [30,33]. Moreover, the transmis- sion profile is symmetrical about (θ = 0) due to the absence of an external magnetic field along x direction [23].…”

Giant Goos-Hänchen Shifts in Au-ITO-TMDCs-Graphene Heterostructure and Its Potential for High Performance Sensor

“…The reflected P-polarized light is collected and analyzed by the photodetector and the angle of incidence is θ. The SF11 glass is adopted as the prism because of its high refractive index [44]. The Au thin film coated BK7 glass slide is attached to the base of an equilateral prism made of high refractive index glass through index matching fluid [45].…”