Probing magnetism in 2D van der Waals crystalline insulators via electron tunneling

TL;DR

This study demonstrates how electron tunneling can be used to probe magnetic states and excitations in atomically thin layered magnetic insulators like CrI3, revealing their magnetic transitions and collective excitations.

Contribution

It introduces a tunneling-based method to characterize magnetism in 2D van der Waals insulators, providing new insights into their magnetic properties and excitations.

Findings

Detection of magnetic ground state and inter-layer coupling

Observation of a field-induced metamagnetic transition

Measurement of magnetic excitations (magnons) in CrI3

Abstract

Magnetic insulators are a key resource for next-generation spintronic and topological devices. The family of layered metal halides promises ultrathin insulating multiferroics, spin liquids, and ferromagnets, but new characterization methods are required to unlock their potential. Here, we report tunneling through the layered magnetic insulator CrI3 as a function of temperature and applied magnetic field. We electrically detect the magnetic ground state and inter-layer coupling and observe a field-induced metamagnetic transition. The metamagnetic transition results in magnetoresistances of 95%, 300%, and 550% for bilayer, trilayer, and tetralayer CrI3 barriers, respectively. We further measure inelastic tunneling spectra for our junctions, unveiling a rich spectrum of collective magnetic excitations (magnons) in CrI3. Our results establish vertical tunneling as a versatile probe of magnetism in atomically thin insulators.