Spin-orbit torque switching in sputtered BiTe driven by spin Hall effect

Tian-Yue Chen^1*, Cheng-Wei Peng¹, Wei-Bang Liao¹, Tsung-Yu Tsai¹, Hung-Wei Yen¹, Chi-Feng Pai¹

¹Materials Science and Engineering, National Taiwan University, Taipei, Taiwan

* Presenter:Tian-Yue Chen, email:f05527067@ntu.edu.tw

Topological insulators (TIs) are the most popular spin-orbit torque (SOT) materials in spintronics society. TIs possess extremely high damping-like (DL) SOT efficiency due to the spin momentum locking from the topological surface state (TSS). Compared with the transition metals, whose SOT comes from the bulk spin Hall effect (SHE) and the DL-SOT efficiencies range from 10-30% [1-3], whereas the TIs can reach over 100%. However, most works prepared TIs are utilizing the molecular beam epitaxy (MBE), which is hard to employ in the industrial fabrication process. Therefore, integrating the industry-favored tool to prepare large SOT materials becomes a crucial issue.
In this work, we use conventional magnetron sputtering to deposit the non-epitaxial BiTe/ferromagnet heterostructures. The harmonic voltage measurement [4] and the hysteresis loop shift measurement [5] are performed to characterize the DL-SOT efficiency. Even without the TSS, the DL-SOT efficiency of the non-epitaxial BiTe can reach values greater than 100% at room temperature. From the thickness dependence analysis, we conclude that the SOT in such non-epitaxial chalcogenide is not solely from the interfacial effects, bulk SHE also has a significant contribution. Moreover, the current-induced magnetization switching is demonstrated in these BiTe-based heterostructure, which indicates the non-epitaxial chalcogenide materials are potentially efficient SOT sources in future SOT magnetic memory devices. [6]

References
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[2] L. Liu, T. Moriyama, D. Ralph, and R. Buhrman, Physical review letters 106, 036601 (2011).
[3] C.-F. Pai, L. Liu, Y. Li, H. W. Tseng, D. C. Ralph, and R. A. Buhrman, Applied Physics Letters 101, 122404 (2012).
[4] M. Hayashi, J. Kim, M. Yamanouchi, and H. Ohno, Physical Review B 89, 144425 (2014).
[5] C.-F. Pai, M. Mann, A. J. Tan, and G. S. D. Beach, Physical Review B 93, 144409 (2016).
[6] T.-Y. Chen, C.-W. Peng, T.-Y. Tsai, W.-B. Liao, C.-T. Wu, H.-W. Yen, and C.-F. Pai, ACS Applied Materials & Interfaces 12, 7788-7794 (2020).

Keywords: Spin Hall effect, Spin-orbit torque, Topological insulator, Chalcogenide