Sign-reversible valley-dependent Berry phase effects in 2D valley-half-semiconductors

TL;DR

This paper proposes a general scheme to control valley-dependent Berry phase effects in 2D valley-half-semiconductors, demonstrating sign reversals and quantized transport phenomena through external stimuli, advancing valleytronics and spintronics.

Contribution

It introduces a universal framework for manipulating valley-dependent Berry phases and demonstrates sign changes and quantized effects in a specific material example.

Findings

Sign change of valley-dependent Berry phase effects driven by external means.

Quantized valley anomalous transport phenomena observed.

Framework applicable for multifunctional quantum device design.

Abstract

Manipulating valley-dependent Berry phase effects provides remarkable opportunities for both fundamental research and practical applications. Here, by referring to effective model analysis, we propose a general scheme for realizing topological magneto-valley phase transitions. More importantly, by using valley-half-semiconducting VSi2N4 as an outstanding example, we investigate sign change of valley-dependent Berry phase effects which drive the change-in-sign valley anomalous transport characteristics via external means such as biaxial strain, electric field, and correlation effects. As a result, this gives rise to quantized versions of valley anomalous transport phenomena. Our findings not only uncover a general framework to control valley degree of freedom, but also motivate further research in the direction of multifunctional quantum devices in valleytronics and spintronics.