Near-Room-Temperature Field-Controllable Exchange Bias in 2D van der Waals Ferromagnet Fe3GaTe2

TL;DR

This paper demonstrates a near-room-temperature exchange bias in 2D Fe3GaTe2, tunable by magnetic field, with a novel defect-based exchange spring mechanism, advancing 2D spintronics technology.

Contribution

It reports the first near-room-temperature exchange bias in 2D vdW ferromagnet Fe3GaTe2 and introduces a defect-driven exchange spring model for EB.

Findings

Achieved 280 K blocking temperature for EB in Fe3GaTe2.

Demonstrated isothermal tuning of bias direction and magnitude.

Observed cumulative minor loops and multiple reversal paths.

Abstract

Exchange bias (EB) is a cornerstone of modern magnetic memory and sensing technologies. Its extension to the realm of two-dimensional (2D) van der Waals (vdW) magnets holds promise for revolutionary advancements in miniaturized and efficient atomic spintronic devices. However, the blocking temperature of EB in 2D vdW magnets is currently well below room temperature ~130 K. This study reports a robust EB phenomenon in Fe3GaTe2 thin-layer devices, which significantly increases the blocking temperature to a near-room-temperature record of 280 K. Both the bias direction and magnitude can be isothermally tuned by adjusting the field sweep range, in striking contrast to the conventional EB in ferromagnetic/antiferromagnetic (FM/AFM) bilayers. We propose an exchange spring model in which crystal defects with higher coercivity act as the pivotal pinning source for the observed EB phenomenon, deviating from the conventional FM/AFM interface mechanism. Cumulative growth of minor loops and multiple magnetization reversal paths are observed in field cycles below the saturation field, consistent with the hard FM defects behavior of our exchange spring model. These findings provide insights into the complex magnetic order in 2D ferromagnets and open new avenues for developing practical ultrathin vdW spintronic devices with EB-like properties at room temperature.