Choi Jae Won, Park Chanho, Kim Gil-Sung, Cho Jung-Min, Park No-Won, Kim Yun-Ho, Jung Min Young, Chang Seo Hyoung, Akhanda Md Sabbir, Shivaram Bellave, Bennett Steven P, Zebarjadi Mona, Lee Sang-Kwon
Department of Physics, Chung-Ang University, Seoul, 06974, Republic of Korea.
Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA, 22904, USA.
Small. 2024 Oct;20(43):e2403315. doi: 10.1002/smll.202403315. Epub 2024 Jun 22.
Iron rhodium (FeRh) undergoes a first-order anti-ferromagnetic to ferromagnetic phase transition above its Curie temperature. By measuring the anomalous Nernst effect (ANE) in (110)-oriented FeRh films on AlO substrates, the ANE thermopower over a temperature range of 100-350 K is observed, with similar magnetic transport behaviors observed for in-plane magnetization (IM) and out-of-plane magnetization (PM) configurations. The temperature-dependent magnetization-magnetic field strength (M-H) curves revealed that the ANE voltage is proportional to the magnetization of the material, but additional features magnetic textures not shown in the M-H curves remained intractable. In particular, a sign reversal occurred for the ANE thermopower signal near zero field in the mixed-magnetic-phase films at low temperatures, which is attributed to the diamagnetic properties of the AlO substrate. Finite element method simulations associated with the Heisenberg spin model and Landau-Lifshitz-Gilbert equation strongly supported the abnormal heat transport behavior from the AlO substrate during the experimentally observed magnetic phase transition for the IM and PM configurations. The results demonstrate that FeRh films on an AlO substrate exhibit unusual behavior compared to other ferromagnetic materials, indicating their potential for use in novel applications associated with practical spintronics device design, neuromorphic computing, and magnetic memory.
铁铑（FeRh）在其居里温度以上会经历从反铁磁到铁磁的一级相变。通过测量AlO衬底上（110）取向的FeRh薄膜中的反常能斯特效应（ANE），观察到了100 - 350 K温度范围内的ANE热功率，并且对于面内磁化（IM）和面外磁化（PM）配置观察到了类似的磁输运行为。温度依赖的磁化强度 - 磁场强度（M - H）曲线表明，ANE电压与材料的磁化强度成正比，但M - H曲线中未显示的磁织构等其他特征仍然难以处理。特别是，在低温下的混合磁相薄膜中，ANE热功率信号在零场附近出现了符号反转，这归因于AlO衬底的抗磁特性。与海森堡自旋模型和朗道 - 里夫希茨 - 吉尔伯特方程相关的有限元方法模拟有力地支持了在实验观察到的IM和PM配置的磁相变过程中来自AlO衬底的异常热输运行为。结果表明，与其他铁磁材料相比，AlO衬底上的FeRh薄膜表现出不同寻常的行为，表明它们在与实际自旋电子器件设计、神经形态计算和磁存储相关的新型应用中的潜力。
