Xiao Han, Lyu Bingbing, Mi Mengjuan, Yuan Jian, Zhang Xiandong, Yu Lixuan, Cui Qihui, Wang Chaofan, Song Jun, Huang Mingyuan, Tian Yufeng, Liu Liang, Taniguchi Takashi, Watanabe Kenji, Liu Min, Guo Yanfeng, Wang Shanpeng, Wang Yilin
School of Integrated Circuits, Shandong Technology Center of Nanodevices and Integration, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
Adv Sci (Weinh). 2024 Dec;11(48):e2409210. doi: 10.1002/advs.202409210. Epub 2024 Nov 4.
Exchange bias (EB) in antiferromagnetic (AFM)/ferromagnetic heterostructures is crucial for the advancement of spintronic devices and has attracted significant attention. The common EB effect in van der Waals heterostructures features a low blocking temperature (T) and a single polarity. In this work, a significant EB effect with a T up to 150 K is observed in FePS/FeGaTe heterostructures, and in particular, the EB exhibits an unusual temperature-dependent polarity-reversal behavior. Under a high positive field-cooling condition (e.g., μH ≥ 0.5 T), a negative EB field (H) is observed at low temperatures, and with increasing temperature, the H crosses zero at ≈20 K, subsequently becomes positive and later approaches zero again at T. A model composed of a top FePS/interfacial FePS/FeGaTe sandwich structure is proposed. The charge transfer from FeGaTe to FePS at the interface induces net magnetic moments (∆M) in FePS. The interface favors AFM coupling, and thus the reversal of ∆M of the interfacial FePS leads to the polarity-reversal of EB. Moreover, the EB can be extended to the bare FeGaTe region of the FeGaTe flake partially covered by FePS. This work provides opportunities for a deeper understanding of the EB effect and opens a new route toward constructing novel spintronic devices.
反铁磁（AFM）/铁磁异质结构中的交换偏置（EB）对于自旋电子器件的发展至关重要，并已引起了广泛关注。范德华异质结构中常见的EB效应具有低阻塞温度（T）和单一极性。在这项工作中，在FePS/FeGaTe异质结构中观察到了显著的EB效应，其T高达150 K，特别是EB表现出异常的温度依赖性极性反转行为。在高正场冷却条件下（例如，μH≥0.5 T），在低温下观察到负的EB场（H），并且随着温度升高，H在≈20 K时穿过零，随后变为正，并在T时再次接近零。提出了一种由顶部FePS/界面FePS/FeGaTe三明治结构组成的模型。FeGaTe在界面处向FePS的电荷转移在FePS中诱导出净磁矩（∆M）。界面有利于AFM耦合，因此界面FePS的∆M反转导致EB的极性反转。此外，EB可以扩展到FePS部分覆盖的FeGaTe薄片的裸FeGaTe区域。这项工作为更深入理解EB效应提供了机会，并为构建新型自旋电子器件开辟了一条新途径。
