Puthirath Balan Aravind, Kumar Aditya, Scholz Tanja, Lin Zhongchong, Shahee Aga, Fu Shuai, Denneulin Thibaud, Vas Joseph, Kovács András, Dunin-Borkowski Rafal E, Wang Hai I, Yang Jinbo, Lotsch Bettina V, Nowak Ulrich, Kläui Mathias
Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany.
Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
ACS Nano. 2024 Mar 19;18(11):8383-8391. doi: 10.1021/acsnano.3c13034. Epub 2024 Mar 4.
Two-dimensional van der Waals (vdW) heterostructures are an attractive platform for studying exchange bias due to their defect-free and atomically flat interfaces. Chromium thiophosphate (CrPS), an antiferromagnetic material, possesses uncompensated magnetic spins in a single layer, rendering it a promising candidate for exploring exchange bias phenomena. Recent findings have highlighted that naturally oxidized vdW ferromagnetic FeGeTe exhibits exchange bias, attributed to the antiferromagnetic coupling of its ultrathin surface oxide layer (O-FGT) with the underlying unoxidized FeGeTe. Anomalous Hall measurements are employed to scrutinize the exchange bias within the CrPS/(O-FGT)/FeGeTe heterostructure. This analysis takes into account the contributions from both the perfectly uncompensated interfacial CrPS layer and the interfacial oxide layer. Intriguingly, a distinct and nonmonotonic exchange bias trend is observed as a function of temperature below 140 K. The occurrence of exchange bias induced by a "preset field" implies that the prevailing phase in the polycrystalline surface oxide is ferrimagnetic FeO. Moreover, the exchange bias induced by the ferrimagnetic FeO is significantly modulated by the presence of the van der Waals antiferromagnetic CrPS layer, forming a heterostructure, along with additional iron oxide phases within the oxide layer. These findings underscore the intricate and complex nature of exchange bias in van der Waals heterostructures, highlighting their potential for tailored manipulation and control.
二维范德华（vdW）异质结构因其无缺陷且原子级平整的界面，是研究交换偏置的一个有吸引力的平台。硫代磷酸铬（CrPS）是一种反铁磁材料，在单层中具有未补偿的磁自旋，使其成为探索交换偏置现象的有前途的候选材料。最近的研究结果表明，自然氧化的范德华铁磁体FeGeTe表现出交换偏置，这归因于其超薄表面氧化物层（O-FGT）与下层未氧化的FeGeTe的反铁磁耦合。采用反常霍尔测量来研究CrPS/(O-FGT)/FeGeTe异质结构中的交换偏置。该分析考虑了完全未补偿的界面CrPS层和界面氧化物层的贡献。有趣的是，在低于140 K的温度下，观察到了作为温度函数的独特且非单调的交换偏置趋势。由“预设场”引起的交换偏置的出现意味着多晶表面氧化物中的主要相是亚铁磁性FeO。此外，亚铁磁性FeO引起的交换偏置受到范德华反铁磁CrPS层的存在以及氧化物层内额外的氧化铁相的显著调制，形成了一种异质结构。这些发现强调了范德华异质结构中交换偏置的复杂性质，突出了它们进行定制操纵和控制的潜力。
