Wafer-scale two-dimensional ferromagnetic Fe3GeTe2 thin films grown by molecular beam epitaxy

TLDR

Layered two‑dimensional ferromagnetic materials have attracted interest for low‑dimensional magnetic and spintronic devices, ferromagnetism persists down to monolayer, and studying their distinct magnetic properties at low dimensionality is therefore important. The study reports wafer‑scale growth of Fe₃GeTe₂ thin films by molecular beam epitaxy and demonstrates that their magnetic properties can be tuned by Fe composition and coupling to antiferromagnetic MnTe. A 2D layer‑by‑layer growth mode was achieved using in‑situ reflection high‑energy electron diffraction oscillations, yielding a well‑defined interlayer spacing of 0.82 nm along the {002} surface. The films exhibit a c‑axis magnetic easy axis with a Curie temperature of 216.4 K that increases with Fe content, a 50 % rise in coercive field from 0.65 to 0.94 T when coupled to MnTe, and overall controllable magnetic properties that make Fe₃GeTe₂ promising for spintronic applications and for exploring physics with other 2D superconductors and topological materials.

Abstract

Abstract Recently, layered two-dimensional ferromagnetic materials (2D FMs) have attracted a great deal of interest for developing low-dimensional magnetic and spintronic devices. Mechanically exfoliated 2D FMs were discovered to possess ferromagnetism down to monolayer. It is therefore of great importance to investigate the distinct magnetic properties at low dimensionality. Here, we report the wafer-scale growth of 2D ferromagnetic thin films of Fe 3 GeTe 2 via molecular beam epitaxy, and their exotic magnetic properties can be manipulated via the Fe composition and the interface coupling with antiferromagnetic MnTe. A 2D layer-by-layer growth mode has been achieved by in situ reflection high-energy electron diffraction oscillations, yielding a well-defined interlayer distance of 0.82 nm along {002} surface. The magnetic easy axis is oriented along c -axis with a Curie temperature of 216.4 K. Remarkably, the Curie temperature can be enhanced when raising the Fe composition. Upon coupling with MnTe, the coercive field dramatically increases 50% from 0.65 to 0.94 Tesla. The large-scale layer-by-layer growth and controllable magnetic properties make Fe 3 GeTe 2 a promising candidate for spintronic applications. It also opens up unprecedented opportunities to explore rich physics when coupled with other 2D superconductors and topological matters.