# Valley-Contrasting Orbital Magnetic Moment Induced Negative Magnetoresistance

## TL;DR

This paper reveals a new mechanism for negative magnetoresistance driven by valley-contrasting orbital magnetic moments, demonstrated through a 2D multi-valley model and relevant to ionic-liquid gated gapped graphene.

## Contribution

It introduces a novel physical mechanism linking valley-contrasting orbital magnetic moments to negative magnetoresistance in 2D materials.

## Key findings

- Giant negative magnetoresistance observed after valley depletion.
- The mechanism is explained by increased carrier density from magnetic gating.
- Relevance to ionic-liquid gated gapped graphene with small effective mass.

## Abstract

The valley-contrasting orbital magnetic moment of Bloch electrons allows the lifting of valley degeneracy by an out-of-plane magnetic field. We demonstrate that this leads to negative magnetoresistance, utilizing a gapped two-dimensional multi-valley model as an example. An intuitive physical picture in terms of the increased carrier density from a magnetic gating effect is proposed for this negative magnetoresistance. In particular, giant negative magnetoresistance is achieved after one of the two valleys is depleted by the magnetic field. This new mechanism of negative magnetoresistance is argued to be relevant in ionic-liquid gated gapped graphene with small effective mass.