Nearly-room-temperature ferromagnetism and tunable anomalous Hall effect in atomically thin Fe4CoGeTe2

TL;DR

This paper reports nearly-room-temperature ferromagnetism and a tunable anomalous Hall effect in atomically thin Fe4CoGeTe2, highlighting its potential for spintronic applications and understanding 2D magnetic materials.

Contribution

It demonstrates nearly-room-temperature ferromagnetism in atomically thin Fe4CoGeTe2 and reveals a thickness-dependent anomalous Hall effect, supported by theoretical calculations.

Findings

Ferromagnetism persists down to bilayer thickness (~2 nm).

Anomalous Hall effect varies with temperature and thickness.

Theoretical models support ferromagnetism in monolayer Fe4CoGeTe2.

Abstract

Itinerant ferromagnetism at room temperature is a key ingredient for spin transport and manipulation. Here, we report the realization of nearly-room-temperature itinerant ferromagnetism in Co doped Fe5GeTe2 thin flakes. The ferromagnetic transition temperature TC (~ 323 K - 337 K) is almost unchanged when thickness is down to 12 nm and is still about 284 K at 2 nm (bilayer thickness). Theoretical calculations further indicate that the ferromagnetism persists in monolayer Fe4CoGeTe2. In addition to the robust ferromagnetism down to the ultrathin limit, Fe4CoGeTe2 exhibits an unusual temperature- and thickness-dependent intrinsic anomalous Hall effect. We propose that it could be ascribed to the dependence of band structure on thickness that changes the Berry curvature near the Fermi energy level subtly. The nearly-room-temperature ferromagnetism and tunable anomalous Hall effect in atomically thin Fe4CoGeTe2 provide opportunities to understand the exotic transport properties of two-dimensional van der Waals magnetic materials and explore their potential applications in spintronics.