Room temperature magnetic vortices in the van der Waals magnet Fe$_5$GeTe$_2$

TL;DR

This study demonstrates the stabilization of magnetic vortices at room temperature in Fe$_5$GeTe$_2$ microstructures using confinement, but finds no significant increase in Curie temperature through patterning.

Contribution

It shows that confinement can stabilize magnetic vortices at room temperature in van der Waals magnets, providing insights into non-collinear magnetic textures.

Findings

Magnetic vortices are stabilized at room temperature in microstructures.

Patterning does not significantly increase the Curie temperature.

Size of micro-discs influences vortex stabilization.

Abstract

We investigate the effect of confinement on the magnetic state of a 12 nm-thick Fe$_5$GeTe$_2$ layer grown by molecular beam epitaxy. We use quantitative scanning NV magnetometry to locally extract the magnetization in rectangular uniformly in-plane magnetized microstructures, showing no enhancement of the Curie temperature compared to magnetization measurements performed before patterning the film, in contrast to previous results obtained on thick Fe$_3$GeTe$_2$ flakes. Under the application of a weak out-of-plane magnetic field, we observe the stabilization of magnetic vortices at room temperature in micrometric squares. Finally, we highlight the effect of the size of the patterned micro-discs and micro-squares on the stabilization of the vortices using experiments and micromagnetic simulations. Our work thus proposes and demonstrates a way to stabilize non-collinear textures at room temperature in a van der Waals magnets using confinement, although we also show that this approach alone is not successful to enhance the Curie temperature of Fe$_5$GeTe$_2$ significantly above 300 K.