Wide field imaging of van der Waals ferromagnet Fe3GeTe2 by spin defects in hexagonal boron nitride

TLDR

Color centers in van der Waals materials, especially in hexagonal boron nitride, are promising for quantum sensing due to their accessible spins and ease of device integration. The study aims to image ferromagnetism in Fe3GeTe2/hBN heterostructures using boron vacancy spin defects in hBN. These spin defects serve as nanoscale quantum probes that perform spin relaxometry imaging of the ferromagnetic layers. Spin relaxometry revealed spatially varying magnetic fluctuations in Fe3GeTe2, peaking near the Curie temperature, demonstrating that hBN spin defects can precisely probe local magnetism in layered materials.

Abstract

Emergent color centers with accessible spins hosted by van der Waals materials have attracted substantial interest in recent years due to their significant potential for implementing transformative quantum sensing technologies. Hexagonal boron nitride (hBN) is naturally relevant in this context due to its remarkable ease of integration into devices consisting of low-dimensional materials. Taking advantage of boron vacancy spin defects in hBN, we report nanoscale quantum imaging of low-dimensional ferromagnetism sustained in Fe3GeTe2/hBN van der Waals heterostructures. Exploiting spin relaxometry methods, we have further observed spatially varying magnetic fluctuations in the exfoliated Fe3GeTe2 flake, whose magnitude reaches a peak value around the Curie temperature. Our results demonstrate the capability of spin defects in hBN of investigating local magnetic properties of layered materials in an accessible and precise way, which can be extended readily to a broad range of miniaturized van der Waals heterostructure systems.