Online Spintronics Seminar #37: Chi Feng Pai скачать в хорошем качестве

Online Spintronics Seminar #37: Chi Feng Pai

Probing Spin-Orbit Torque Switching Through Unidirectional Magnetoresistance This online seminar was given on August 18, 2020, by Prof. Chi-Feng Pai of National Taiwan University. Please refer to https://www.spintalks.org for more information about the Online Spintronics Seminar Series. Abstract: It has been shown that the spin Hall effect (SHE) from heavy transition metals and other emergent materials systems can generate sufficient spin-orbit torque (SOT) and further produce current-induced magnetization switching in the adjacent ferromagnetic layer. However, if the ferromagnetic layer has in-plane magnetic anisotropy, probing such switching phenomenon typically relies on tunnelling magnetoresistance (TMR) measurement of nano-sized magnetic tunnel junctions (challenging in device making), differential planar Hall voltage (DPHE) measurement (complicated in measurement configuration), or Kerr imaging approaches (relies on optical response). In this presentation, I will first show that in magnetic heterostructures with spin Hall metals, there exist current-induced in-plane spin Hall effective fields (SHF) [1] and unidirectional magnetoresistance (UMR) [2] that will modify their anisotropic magnetoresistance behaviour. By analysing the response of magnetoresistance under such influences, one can directly and electrically probe magnetization switching driven by the spin-orbit torque, even in common micron-sized Hall-bar devices. This pump-probe method therefore allows for efficient and direct determination of key parameters from spin-orbit torque switching events without lengthy device fabrication processes [3]. [1] X. Fan, J. Wu, Y. Chen, M. J. Jerry, H. Zhang, and J. Q. Xiao, Observation of the nonlocal spin-orbital effective field, Nat. Commun. 4, 1799 (2013). [2] C. O. Avci, K. Garello, A. Ghosh, M. Gabureac, S. F. Alvarado, and P. Gambardella, Unidirectional spin Hall magnetoresistance in ferromagnet/normal metal bilayers, Nat. Phys. 11, 570 (2015). [3] Y.-T. Liu, T.-Y. Chen, T.-H. Lo, T.-Y. Tsai, S.-Y. Yang, Y.-J. Chang, J.-H. Wei, and C.-F. Pai, Determination of Spin-Orbit Torque Efficiencies in Heterostructures with In-plane Magnetic Anisotropy, Physical Review Applied 13, 044032 (2020).