Gate-controlled magnetic phase transition in a van der Waals magnet Fe$_5$GeTe$_2$

TL;DR

This study demonstrates that electron doping via a protonic gate can induce a magnetic phase transition from ferromagnetic to antiferromagnetic in a thin van der Waals magnet Fe$_5$GeTe$_2$, revealing new control methods for 2D magnetic materials.

Contribution

It is the first to show gate-controlled magnetic phase transition in a vdW itinerant magnet, expanding possibilities for 2D magnetic device applications.

Findings

Electron doping induces FM to AFM transition in Fe$_5$GeTe$_2$.

Magnetic phase transition observed in layers as thin as 6.8 nm.

Potential for high-temperature antiferromagnetic vdW devices.

Abstract

Magnetic van der Waals (vdW) materials, including ferromagnets (FM) and antiferromagnets (AFM), have given access to the investigation of magnetism in two-dimensional (2D) limit and attracted broad interests recently. However, most of them are semiconducting or insulating and the vdW itinerant magnets, especially vdW itinerant AFM, are very rare. Here, we studied the anomalous Hall effect of a vdW itinerant magnet Fe$_5$GeTe$_2$ (F5GT) with various thicknesses down to 6.8 nm (two unit cells). Despite the robust ferromagnetic ground state in thin-layer F5GT, however, we show that the electron doping implemented by a protonic gate can eventually induce a magnetic phase transition from FM to AFM. Realization of an antiferromagnetic phase in F5GT highlights its promising applications in high-temperature antiferromagnetic vdW devices and heterostructures.