Argonne National Laboratory

Insulating nanomagnets driven by spin torque

Jungfleisch, Matthias; Ding, Junjia; Zhang, Wei; Jiang, Wanjun; Pearson, John; Novosad, Valentine; Hoffmann, Axel
Publication Year
Publication Type 
Magnetic insulators, such as yttrium iron garnet (Y3Fe5O12), are ideal materials for ultra-low power spintronics applications due to their low energy dissipation and efficient spin current generation and transmission. Recently, it has been realized that spin dy- namics can be driven very effectively in micrometer-sized Y3Fe5O12/Pt heterostructures by spin-Hall effects. We demonstrate here the excitation and detection of spin dynam- ics in Y3Fe5O12/Pt nanowires by spin-torque ferromagnetic resonance. The nanowires defined via electron-beam lithography are fabricated by conventional room tempera- ture sputtering deposition on Gd3Ga5O12 substrates and lift-off. We observe field-like and anti-damping-like torques acting on the magnetization precession, which are due to simultaneous excitation by Oersted fields and spin-Hall torques. The Y3Fe5O12/Pt nanowires are thoroughly examined over a wide frequency and power range. We observe a large change in the resonance field at high microwave powers, which is attributed to a decreasing effective magnetization due to microwave absorption. By comparing dif- ferent nanowire widths, the importance of geometrical confinements for magnetization dynamics becomes evident. Our results are the first stepping stones toward the realiza- tion of integrated magnonic logic devices based on insulators, where nanomagnets play an essential role.
Jungfleisch, Matthias, Junjia Ding, Wei Zhang, Wanjun Jiang, John Pearson, Valentine Novosad and Axel Hoffmann. "Insulating nanomagnets driven by spin torque." Nano Letters 17, no. 1 2017: 8-14. doi: 10.1021/acs.nanolett.6b02794.