Unraveling effects of competing interactions and frustration in vdW ferromagnetic Fe3GeTe2 nanoflake devices

Abstract

Two-dimensional (2D) van der Waals (vdW) magnets and devices have garnered significant attention owing to the stabilization of long-range magnetic order down to atomic limit, and the prospect for quantum devices with unique functionalities. To achieve this objective, clarification of magnetotransport properties and understanding of the relevant interactions with lowering of dimensions are of extreme importance. Here, the magnetotransport properties of few atomic layer Fe3GeTe2 and (Co0.25Fe0.75)3GeTe2 nanoflake devices have been investigated. Magnetotransport investigations with applied magnetic field along the easy-axis show anomalous Hall effect, while that for applied magnetic field along the hard-axis reveal an unusual behavior. Atomistic calculations considering the presence of antiferromagnetic, ferromagnetic, and local symmetry-breaking interactions reveal the critical role of magnetic frustration effect assisted by thermal fluctuations, leading to a non-zero scalar spin chirality manifesting in an unconventional Hall effect. The present result clarifies the underlying interactions in few-layer 2D vdW ferromagnetic material system, important for the understanding of non-collinear spin configurations in vdW magnets for 2D spintronic devices.