Photoenhanced spin/valley polarization and tunneling magnetoresistance in ferromagnetic-normal-ferromagnetic silicene junction

TL;DR

This paper proposes a method to enhance spin and valley polarization, as well as tunneling magnetoresistance, in silicene junctions using off-resonant circularly polarized light, with potential applications in spintronics.

Contribution

It introduces a novel approach to control spin and valley polarization and TMR in silicene junctions via off-resonant circularly polarized light, independent of barrier height.

Findings

Full spin polarization achievable with specific light intensities.

Reversal of spin polarization with incident energy changes.

Perfect valley polarization sensitive to electric field.

Abstract

We theoretically demonstrate a simple way to significantly enhance the spin/valley polarizations and tunnel- ing magnetoresistnace (TMR) in a ferromagnetic-normal-ferromagnetic (FNF) silicene junction by applying a circularly polarized light in off-resonant regime to the second ferromagnetic (FM) region. We show that the fully spin-polarized current can be realized in certain ranges of light intensity. Increasing the incident energy in the presence of light will induce a transition of perfect spin polarization from positive to negative or vice versa depending on magnetic configuration (parallel or anti-parallel) of FNF junction. Additionally, under a circularly polarized light, valley polarization is very sensitive to electric field and the perfect valley polarization can be achieved even when staggered electric field is much smaller than exchange field. The most important result we would like to emphasize in this paper is that the perfect spin polarization and 100% TMR induced by a circularly polarized light are completely independent of barrier height in normal region. Furthermore, the sign reversal of TMR can be observed when the polarized direction of light is changed. A condition for observing the 100% TMR is also reported. Our results are expected to be informative for real applications of FNF silicene junction, especially in spintronics.