Near-room-temperature exchange bias in surface-oxidized Fe$lt;sub$gt;3$lt;/sub$gt;GaTe$lt;sub$gt;2$lt;/sub$gt; revealed by reflective magnetic circular dichroism

Exchange bias, which typically requires a coupled ferromagnetic and antiferromagnetic interface, plays a key role in enhancing data storage technologies by reducing noise and improving signal readability. In this study, we investigate the exchange bias phenomenon in surface-oxidized van der Waals material Fe₃GaTe₂, which exhibits a blocking temperature of approximately 280 K &#x2014; near room temperature. This behavior is particularly significant, as achieving room-temperature exchange bias has been challenging, potentially due to the lack of high-N&#x00E9;el-temperature van der Waals antiferromagnetic materials. Using <i>ab initio</i> calculations and magneto-optical methods, we propose a model to explain the origin of the exchange bias, thereby circumventing the need for complex fabrication typically required in transport measurements. Our findings suggest that surface oxidation plays a crucial role in realizing exchange bias behavior, which is strongly dependent on temperature, interfacial spin-pinning states, and the interplay between ferromagnetic and antiferromagnetic interactions. We also examine the stability and uniformity of this behavior in flakes of various thicknesses. These insights provide valuable understanding of near-room-temperature exchange bias in van der Waals materials, opening up possibilities for their integration into next-generation spintronic and data storage applications.