Large magnetoresistance dips and perfect spin-valley filter induced by topological phase transitions in silicene

TL;DR

This paper explores how topological phase transitions in silicene can be used to control spin-valley currents and induce large magnetoresistance dips, highlighting silicene's potential for spin-valleytronic applications.

Contribution

It demonstrates that electric, exchange fields, and circularly polarized light can precisely control spin-valley filtering via topological phase transitions in silicene.

Findings

Four groups of spin-valley currents can be perfectly filtered.

Large magnetoresistance dips are directly induced by topological phase transitions.

Electrons obeying zero-Chern number are allowed to transport at transition points.

Abstract

Spin-valley transport and magnetoresistance are investigated in silicene-based N/TB/N/TB/N junction where N and TB are normal silicene and topological barriers. The topological phase transitions in TB's are controlled by electric, exchange fields and circularly polarized light. As a result, we find that by applying electric and exchange fields, four groups of spin-valley currents are perfectly filtered, directly induced by topological phase transitions. Control of currents, carried by single, double and triple channels of spin-valley electrons in silicene junction, may be achievable by adjusting magnitudes of electric, exchange fields and circularly polarized light. We may identify that the key factor behind the spin-valley current filtered at the transition points may be due to zero and non-zero Chern numbers. Electrons that are allowed to transport at the transition points must obey zero-Chern number which is equivalent to zero mass and zero-Berry's curvature, while electrons with non-zero Chern number are perfectly suppressed. Very large magnetoresistance dips are found directly induced by topological phase transition points. Our study also discusses the effect of spin-valley dependent Hall conductivity at the transition points on ballistic transport and reveals the potential of silicene as a topological material for spin-valleytronics.