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Séminaire - Tomohiro Taniguchi

Mardi 30 janivier à 15h00, Tomohiro Taniguchi (National Institute of Advanced Industrial Science and Technology (AIST), Japon) donnera un séminaire salle 1B2-106 (Palaiseau) sur le thème : "Spin anomalous Hall effect : proposal and experimental observation"

Agenda

  • Mardi 30 janvier 2018 15:00-16:00 - Tomohiro Taniguchi - National Institute of Advanced Industrial Science and Technology

    Séminaire - Tomohiro Taniguchi

    Résumé : The spin Hall effect originated from the spin-orbit effects in nonmagnetic heavy metals have drawn enormous attention because of their potential application to practical devices. An in-plane electric field applied to the nonmagnet in a ferromagnetic/nonmagnetic bilayer injects spin current into the attached ferromagnet and excites spin-transfer torque. Recent experiments have demonstrated switching of a perpendicular ferromagnet by this spin-transfer torque [1].
    Spin-orbit effects are also observed in ferromagnets in the anomalous Hall effect. We developed a theory of spin-transfer torque excited by the anomalous Hall effect in a ferromagnetic bilayer [2]. It is shown that the spin-transfer torque can point to an arbitrary direction, in contrast to spin-Hall systems where the direction of the spin-transfer torque is geometrically determined. It enables us to control the magnetization more efficiently than with spin-Hall systems. For example, the spin-transfer torque enables us to switch another perpendicular ferromagnet with low current and high accuracy. In this talk, we will show the basis of our idea and the details of the calculation results. In addition, we will report our recent experimental results on the efficiency of the spin-transfer torque by the anomalous Hall effect. We performed the spin-torque ferromagnetic resonance (FMR) experiment in CoFeB/Cu/NiFe trilayer, and evaluated that the efficiency in CoFeB is about 15% [3].
    [1] L. Liu, O. J. Lee, T. J. Gudmundsen, D. C. Ralph, and R. A. Buhrman, Phys. Rev. Lett. 109,096602 (2012).
    [2] T. Taniguchi, J. Grollier, and M. D. Stiles, Phys. Rev. Applied 3, 044001 (2015).
    [3] S. Iihama, T. Taniguchi, K. Yakushiji, A. Fukushima, Y. Shiota, S. Tsunegi, R. Hiramatsu, S. Yuasa, Y. Suzuki, and H. Kubota, accepted to Nature Electronics.


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