Gate control of 2D magnetism in tri- and four-layers $\rm CrI_3$/graphene heterostructures

TL;DR

This study investigates how gate voltage and magnetic field influence the electronic and magnetic proximity effects in graphene/CrI_3 heterostructures, revealing tunable quantum Hall effects without direct magnetic exchange coupling.

Contribution

It demonstrates gate and magnetic field tunability of proximity effects in graphene/CrI_3 heterostructures, highlighting control over conduction band alignment and quantum Hall phenomena.

Findings

Gate voltage controls conduction band alignment.

Coexistence of normal and anomalous quantum Hall effects.

Magnetic field influences conduction band via magnetic states.

Abstract

We conduct experimental studies on the electrical transport properties of monolayer graphene directly covered by a few layers of $\rm CrI_3$. We do not observe the expected magnetic exchange coupling in the graphene but instead discover proximity effects featuring gate and magnetic field tunability. The tunability of gate voltage is manifested in the alignment of the lowest conduction band of $\rm CrI_3$ and the Fermi level of graphene, which can be controlled by the gate voltage. The coexistence of the normal and atypical quantum Hall effects in our device also corresponds to gate-control modulation doping. The lowest conduction band depends on the magnetic states of the $\rm CrI_3$ and can be altered by the magnetic field, which corresponds to the resistance loops during back-and-forth sweeps of the magnetic field. Our results serve as a reference for exploiting the magnetic proximity effects in graphene.