Conductance, Valley and Spin polarization and Tunnelling magneto-resistance in ferromagnetic-normal-ferromagnetic junctions of silicene

TL;DR

This paper studies charge conductance, spin and valley polarization, and tunneling magnetoresistance in ferromagnetic-normal-ferromagnetic silicene junctions, revealing tunable polarization effects and oscillatory TMR behavior influenced by external electric fields.

Contribution

It provides a detailed analysis of how external electric fields and barrier potentials affect conductance, polarization, and TMR in silicene junctions, highlighting unique valley and spin effects unlike graphene.

Findings

Distinct conductance features for parallel and anti-parallel spin configurations.

TMR can oscillate and change sign with barrier potential and electric field.

Pure valley and spin polarizations can be achieved and tuned.

Abstract

We investigate charge conductance and spin and valley polarization along with the tunnelling magneto-resistance (TMR) in silicene junctions composed of normal silicene and ferromagnetic silicene. We show distinct features of the conductances for parallel and anti-parallel spin configurations and the TMR, as the ferromagnetic-normal-ferromagnetic (FNF) junction is tuned by an external electric field. We analyse the behavior of the charge conductance and valley and spin polarizations in terms of the independent conductances of the different spins at the two valleys and the band structure of ferromagnetic silicene and show how the conductances are affected by the vanishing of the propagating states at one or the other valley. In particular, unlike in graphene, the band structure at the two valleys are independently affected by the spin in the ferromagnetic regions and lead to non-zero, and in certain parameter regimes, pure valley and spin polarizations, which can be tuned by the external electric field. We also investigate the oscillatory behavior of the TMR with respect to the strength of the barrier potential (both spin-independent and spin-dependent barriers) in the normal silicene region and note that in some parameter regimes, the TMR can even go from positive to negative values, as a function of the external electric field.