Large-area synthesis of ferromagnetic Fe$_{5-x}$GeTe$_{2}$/graphene van der Waals heterostructures with Curie temperature above room temperature

TL;DR

This paper reports the scalable synthesis of large-area Fe$_{5-x}$GeTe$_{2}$/graphene heterostructures with ferromagnetic order persisting above room temperature, advancing the integration of 2D ferromagnets into practical devices.

Contribution

It introduces a scalable vdW epitaxy method for growing high-quality ferromagnetic Fe$_{5-x}$GeTe$_{2}$/graphene heterostructures with stable magnetic properties above room temperature.

Findings

Successful large-area growth of heterostructures via vdW epitaxy.

Ferromagnetic order persists above 300 K with perpendicular anisotropy.

Heterostructures maintain high electronic quality of graphene.

Abstract

Van der Waals (vdW) heterostructures combining layered ferromagnets and other two-dimensional (2D) crystals are promising building blocks for the realization of ultra-compact devices with integrated magnetic, electronic and optical functionalities. Their implementation in various technologies depends strongly on the development of a bottom-up scalable synthesis approach allowing to realize highly uniform heterostructures with well-defined interfaces between different 2D layered materials. It also requires that each material component of the heterostructure remains functional, which ideally includes ferromagnetic order above room temperature for 2D ferromagnets. Here, we demonstrate large-area growth of Fe$_{5-x}$GeTe$_{2}$/graphene heterostructures achieved by vdW epitaxy of Fe$_{5-x}$GeTe$_{2}$ on epitaxial graphene. Structural characterization confirmed the realization of a continuous vdW heterostructure film with a sharp interface between Fe$_{5-x}$GeTe$_{2}$ and graphene. Magnetic and transport studies revealed that the ferromagnetic order persists well above 300 K with a perpendicular magnetic anisotropy. In addition, epitaxial graphene on SiC(0001) continues to exhibit a high electronic quality. These results represent an important advance beyond non-scalable flake exfoliation and stacking methods, thus marking a crucial step toward the implementation of ferromagnetic 2D materials in practical applications.