Thermal stability and memristive spin-orbit torque switching at elevated temperature

Wei-Bang Liao^1*, Tian-Yue Chen¹, Yu-Chan Hsiao¹, Chi-Feng Pai^1,2

¹Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
²Center of Atomic Initiative for New Materials, National Taiwan University, Taipei, Taiwan

* Presenter:Wei-Bang Liao, email:f07527093@ntu.edu.tw

Recently, many spin-orbit torque (SOT) related works commit to enhancing the SOT efficiency but largely neglect the thermal stabilities. However, the thermal stability factor is also crucial for robust storage, especially when SOT-based devices integrated with CMOS. The thermal dissipation from transistor can cause the increase of ambient temperature and therefore may affect the performance of SOT efficiency and thermal stability factor. On the other hand, SOT-based devices applied in neuromorphic area flourishes for the potential in memristive switching. The multi-states in memristive switching can be controlled through changing the amplitude and the duration of the applied currents, which has been shown in previous works. However, the thermal effect on memristive switching has not been studied yet.
In this work, through comprehensive temperature-dependent study on standard W/CoFeB/MgO and field-free CoFeB/W/CoFeB/MgO devices, the SOT efficacies of both are found to be invariant from 25 ℃ (298 K) to 80 ℃ (353K).¹ The thermal stability factors are shown to degrade with respect to the increase of ambient temperature.² The limit of the memristive switching window, defined by the upper and lower switching current densities to achieve intermediate states, can be tuned by the applied currents. The size of the memristive switching window remains unchanged by current pulses, whereas significantly shrinks at elevated temperatures. Our finding pose the potentially challenging application of SOT-based device in neuromorphic area at elevated temperature.


References
[1] W.-B. Liao, T.-Y. Chen, Y.-C. Hsiao, and C.-F. Pai, Appl. Phys. Lett. 117, 182402 (2020).
[2] S. Z. Rahaman, I. Wang, T. Chen, C. Pai, D. Wang, J. Wei, H. Lee, Y. Hsin, Y. Chang, S. Yang, Y. Kuo, Y. Su, Y. Chen, K. Huang, C. Wu, and D. Deng, IEEE Electron Device Lett. 39, 1306 (2018).

Keywords: spin-orbit torque, memristive, thermal stability, spin Hall effect