Control of valley optical conductivity and topological phases in buckled hexagonal lattice by orientation of in-plane magnetic field

TL;DR

This paper explores how the orientation of an in-plane magnetic field influences optical conductivity and topological phases in buckled hexagonal lattices like silicene, enabling valley-specific current control and material design.

Contribution

It demonstrates tunable topological phases and valley-locked currents through magnetic field orientation, neglecting spin-orbit effects, and provides a method for valley-specific electronic control.

Findings

Rapid change in longitudinal conductivity with magnetic field angle.

Perfect valley filtering in transverse conductivity.

Valley-locked current control via magnetic field orientation.

Abstract

We investigate the optical conductivity, along with longitudinal and transverse conductivities, in buckled hexagonal lattice such as silicene subjected to both an in-plane magnetic field and a perpendicular electric field. In this model, we neglect the effect of the spin-orbit interaction, which is of a smaller order compared to the strong staggered potential and the next-nearest hoping energy. The orientations of the in-plane magnetic field and the perpendicular electric field give rise to a non-uniform, tunable gap. The Chern number for each valley degree of freedom deviates from being constant but remains steady when summed over the entire Brillouin zone. The longitudinal and transverse currents, in the case of a specific valley, can be selected by adjusting the direction of the electric field in the semimetal phase. Furthermore, the defining characteristics of topological phases induces the rapid change in longitudinal conductivity when varying the angle of orientation of the in-plane magnetic field under monochromatic light, and perfect valley filtering in transverse conductivity. The transverse current associated with a specific valley can be selected when the angle of orientation satisfies the specific conditions. This investigation paves the way for materials design with valley-locked current, using a specific orientation of the in-plane magnetic field.