# Giant enhancement of interlayer exchange in an ultrathin 2D magnet

## TL;DR

This study reveals a ten-fold enhancement of interlayer exchange in ultrathin CrCl3 crystals, linked to stacking order differences, offering new insights into 2D magnetic interactions relevant for spintronics.

## Contribution

It demonstrates a significant increase in interlayer exchange in exfoliated CrCl3 and links it to changes in stacking order, advancing understanding of 2D magnetic properties.

## Key findings

- Ten-fold increase in interlayer exchange in ultrathin CrCl3
- Exfoliated films do not undergo bulk crystallographic phase transition
- Stacking order influences interlayer magnetic interactions

## Abstract

Following the recent isolation of monolayer CrI3, there has been a surge of new two-dimensional van der Waals magnetic materials, whose incorporation in van der Waals heterostructures offers a new platform for spintronics, proximity magnetism, and quantum spin liquids. A primary question in this burgeoning field is how exfoliating crystals to the few-layer limit influences their magnetism. Studies on CrI3 have shown a different magnetic ground state for ultrathin exfoliated films but the origin is not yet understood. Here, we use electron tunneling through few-layer crystals of the layered antiferromagnetic insulator CrCl3 to probe its magnetic order, finding a ten-fold enhancement in the interlayer exchange compared to bulk crystals. Moreover, temperature- and polarization-dependent Raman spectroscopy reveal that the crystallographic phase transition of bulk crystals does not occur in exfoliated films. This results in a different low temperature stacking order and, we hypothesize, increased interlayer exchange. Our study provides new insight into the connection between stacking order and interlayer interactions in novel two-dimensional magnets, which may be relevant for correlating stacking faults and mechanical deformations with the magnetic ground states of other more exotic layered magnets, such as RuCl3.

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Source: https://tomesphere.com/paper/1903.00002