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

Abstract

Low-energy coherent transport and Goos-Hänchen (GH) lateral shift of valley electrons in planar heterojunctions composed of normal MoS2 and ferromagnetic WS2 monolayers are theoretically investigated. Two types of heterojunctions in the forms of WS2/MoS2/WS2 (type-A) and MoS2/WS2/MoS2 (type-B) with incident electrons in MoS2 region are considered in which the lateral shift of electrons is induced by band alignments of the two constituent semiconductors. It is shown that the type-A heterojunction can act as an electron waveguide due to electron confinement between the two WS2/MoS2 interfaces which cause the incident electrons with an appropriate incidence angle to propagate along the interfaces. In this case the spin-and valley-dependent GH shifts of totally reflected electrons from the interface lead to separated electrons with distinct spin-valley indexes after traveling a sufficiently long distance. In type-B heterojunction, however, transmission resonances occur for incident electron beams passing through the structure, and large spin-and valley-dependent lateral shift values in propagating states can be achieved. Consequently, the transmitted electrons are spatially well-separated into electrons with distinct spin-valley indexes. Our findings reveal that the planar heterojunctions of transition metal dichalcogenides can be utilized as spin-valley beam filter and/or splitter without external gating.

Lateral interfaces of transition metal dichalcogenides: A stable tunable one-dimensional physics platform

“…[28][29][30] A HS built of lateral TMD slabs has been predicted to be a high-performance thermoelectric, as the interfaces reduce the thermal conductivity more than electronic mobility. 31 Other proposals for lateral HSs include their use as gateless electronic waveguides and spin valley filters/splitters, 32 as a 1D spin channel driven by just a current flow, 33 as well as optoelectronic applications of spatially indirect excitons in these structures. 34 Motivated by experiments and the unusual nature of lateral HSs, we study their role in mediating magnetic interactions between impurities at the interface.…”

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

“…An increasing number of experimental and theoretical efforts have started exploring effective uses for these lateral interfaces, in areas as diverse as optics, magnetism, and transport. Section 3.2.1 shows studies in optics, which have addressed excitonic effects around the interface [130,131], as well as wave guiding and spin-valley selection effects [132].…”

“…In both cases, the incident electron comes from MoS 2 , since its CBM is lower than in WS 2 . Reprinted with permission from [132]. Copyright 2018 AIP Publishing, Journal of Applied Physics.…”

“…A different study on transport by Ghadiri et al [132] considers a possible Goos-Hänchen lateral shift of valley electrons arriving at the interfacial scattering region, in lateral HSs of normal MoS 2 and 'ferromagnetic' WS 2 , in WS 2 -MoS 2 -WS 2 and MoS 2 -WS 2 -MoS 2 quantum well systems. The magnetic TMD is achieved by deposition on a magnetic insulator system.…”

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

“…Das et al researched the GH shifts of fundamental Gaussian beams on the surfaces of monolayer MoS 2 , TMDCs, and direct band gap semiconductor in detail [42]. The spin-valley transport and GH effect of the transmitted and reflected electrons in the gated monolayer WS 2 are considered [43]. In the SPR structure coated with graphene and MoS 2 heterojunction, the GH shift is significantly enhanced to 235.8 λ [18].…”