Imaging current control of magnetization in Fe$_3$GeTe$_2$ with a widefield nitrogen-vacancy microscope

TL;DR

This study demonstrates the use of widefield NV microscopy to visualize and analyze current-induced magnetization changes and domain-wall motion in thin flakes of the vdW ferromagnet Fe$_3$GeTe$_2$, revealing efficient current control of magnetization.

Contribution

It introduces widefield NV microscopy as an effective tool for imaging current effects in vdW magnets and provides initial evidence of current-induced domain-wall motion in Fe$_3$GeTe$_2$.

Findings

Current injection reduces coercivity at the domain level.

Preliminary evidence of current-induced domain-wall motion at low current densities.

Widefield NV microscopy effectively images spintronic phenomena in vdW magnets.

Abstract

Van der Waals (vdW) magnets are appealing candidates for realising spintronic devices that exploit current control of magnetization (e.g. switching or domain wall motion), but so far experimental demonstrations have been sparse, in part because of challenges associated with imaging the magnetization in these systems. Widefield nitrogen-vacancy (NV) microscopy allows rapid, quantitative magnetic imaging across entire vdW flakes, ideal for capturing changes in the micromagnetic structure due to an electric current. Here we use a widefield NV microscope to study the effect of current injection in thin flakes ($\sim10$nm) of the vdW ferromagnet Fe$_3$GeTe$_2$ (FGT). We first observe current-reduced coercivity on an individual domain level, where current injection in FGT causes substantial reduction in the magnetic field required to locally reverse the magnetisation. We then explore the possibility of current-induced domain-wall motion, and provide preliminary evidence for such a motion under relatively low current densities, suggesting the existence of strong current-induced torques in our devices. Our results illustrate the applicability of widefield NV microscopy to imaging spintronic phenomena in vdW magnets, highlight the possibility of efficient magnetization control by direct current injection without assistance from an adjacent conductor, and motivate further investigations of the effect of currents in FGT and other vdW magnets.