In analogy to electrical currents, which describe a directed transport of electronic charge, spin currents describe the transport of spin angular momentum. Electrons can transport both, electronic charge and angular momentum and the spin-orbit interaction couples the electron spin degree of freedom to the electron momentum. In systems with broken inversion symmetry, control of the magnetization direction by charge currents thus becomes possible.

We excite and detect spin currents and spin-orbit torques from the dc limit to the high GHz frequency range [1-2]. Using non-local magnetotransport measurements, we demonstrated full control of spin-wave damping by dc currents [3]. We study GHz inverse spin-orbit torques in ferromagnet/heavy metal bilayers [2] and develop measurement tools that can be used for rapid, contactless and quantitative assessment of spin-orbit-torque efficiencies in as-grown thin film multilayers [4-5].

We are particularly interested in obtaining a better understanding of the symmetry and magnitude of spin-orbit torques in hybrid systems, including ferromagnetic, antiferromagnetic and/or superconducting thin film layers. Such hybrid systems can then be essential building blocks for magnonic and spintronic devices.

[1]  M. Weiler, M. Althammer, M. Schreier, J. Lotze, M. Pernpeintner, S. Meyer, H. Huebl, R. Gross, A. Kamra, J. Xiao, Y.-T. Chen, H. Jiao, G. E. W. Bauer, and S. T. B. Goennenwein, Experimental Test of the Spin Mixing Interface Conductivity Concept, Phys. Rev. Lett. 111, 176601 (2013).

[2]  M. Weiler, J. M. Shaw, H. T. Nembach, and T. J. Silva, Phase-Sensitive Detection of Spin Pumping via the ac Inverse Spin Hall Effect, Phys. Rev. Lett. 113, 157204 (2014).

[3]  T. Wimmer, M. Althammer, L. Liensberger, N. Vlietstra, S. Geprägs, M. Weiler, R. Gross, and H. Huebl, Spin Transport in a Magnetic Insulator with Zero Effective Damping, Phys. Rev. Lett. 123, 257201 (2019).

[4]  A. J. Berger, E. R. J. Edwards, H. T. Nembach, A. D. Karenowska, M. Weiler, and T. J. Silva, Inductive detection of fieldlike and dampinglike ac inverse spin-orbit torques in ferromagnet/normal-metal bilayers, Phys. Rev. B 97, 094407 (2018).

[5]  M. Meinert, B. Gliniors, O. Gueckstock, T. S. Seifert, L. Liensberger, M. Weiler, S. Wimmer, H. Ebert, and T. Kampfrath, High-Throughput Techniques for Measuring the Spin Hall Effect, Phys. Rev. Applied 14, 064011 (2020).