Direct observation of van der Waals stacking dependent interlayer magnetism

TL;DR

This study demonstrates that the stacking order in 2D CrBr3 layers critically influences interlayer magnetism, with direct atomic-scale observations revealing ferromagnetic or antiferromagnetic coupling depending on stacking configuration.

Contribution

First direct experimental observation of stacking-dependent interlayer magnetism in 2D CrBr3 using advanced microscopy and spectroscopy techniques.

Findings

Monolayer CrBr3 is ferromagnetic.

Bilayer interlayer coupling varies with stacking order.

Stacking control enables manipulation of 2D magnetic properties.

Abstract

Controlling the crystal structure is a powerful approach for manipulating the fundamental properties of solids. Unique to two-dimensional (2D) van der Waals materials, the control can be achieved by modifying the stacking order through rotation and translation between the layers. Here, we report the first observation of stacking dependent interlayer magnetism in the 2D magnetic semiconductor, chromium tribromide (CrBr3), enabled by the successful growth of its monolayer and bilayer through molecular beam epitaxy. Using in situ spin-polarized scanning tunneling microscopy and spectroscopy, we directly correlated the atomic lattice structure with observed magnetic order. We demonstrated that while individual CrBr3 monolayer is ferromagnetic, the interlayer coupling in bilayer depends strongly on the stacking order and can be either ferromagnetic or antiferromagnetic. Our observations provide direct experimental evidence for exploring the stacking dependent layered magnetism, and pave the way for manipulating 2D magnetism with unique layer twist angle control.