Strain-modulated anisotropy of quantum transport properties in single-layer silicene: Spin and valley filtering

Abstract

Strained two-dimensional crystals often offer novel physical properties that are usable to improve their electronic performance. Here we show by the theory of elasticity combined with the tight-binding approximation that local strains in silicene can open up new prospects for generating fully polarized spin and valley currents. The trajectory of electrons flowing through locally strained regions obeys the same behavior as light waves propagating in uniaxial anisotropic materials. The refraction angle of electrons at local strain boundaries exhibits a strong dependence on the valley degree of freedom, allowing for valley filtering based on the strain direction. The ability to control the spin polarization direction additionally requires a perpendicular electric field to be involved in combination with the local strain. Further similarities of the problem with optics of anisotropic materials are elucidated and possible applications in spin- and valleytronic nanodevices are discussed.