Single-Layer ScI2: A Paradigm for Valley-Related Multiple Hall Effect

TL;DR

This paper proposes a strain-engineered mechanism for valley-related multiple Hall effects in 2D hexagonal lattices, demonstrated in single-layer ScI2, revealing new physics and potential applications.

Contribution

It introduces a novel strain-induced valley-contrasted band inversion mechanism and demonstrates its realization in ferromagnetic ScI2, expanding valley physics understanding.

Findings

Valley-related multiple Hall effects appear under specific tensile strain.

Single-layer ScI2 exhibits simultaneous valley Hall and quantum anomalous Hall effects under strain.

The physical mechanism is general and supported by model analysis.

Abstract

Valley-related multiple Hall effect in two-dimensional lattice is of notable interest both for its fundamental physics and for its potential applications. In this work, by means of a low energy kp model analysis, a mechanism of producing valley-related multiple Hall effect in hexagonal lattice via strain engineering is proposed, and a general picture of valley-contrasted band inversion is developed. Through first-principles calculations, this mechanism is further established in a ferromagnetic hexagonal lattice of single-layer ScI2. Single-layer ScI2 prefers in-plane magnetization and exhibits neither anomalous valley Hall effect nor valley-polarized quantum anomalous Hall effect in nature. Remarkably, these two Hall effects emerge simultaneously in this system under 4.705% tensile strain and disappear simultaneously when further increasing strain, suggesting the exotic valley-related multiple Hall effect. The underlying physical mechanism is revealed using a model analysis and is generally applicable. Our work greatly enriches the valley-related physics.