Jungfleisch, Matthias; Ding, Junjia; Zhang, Wei; Jiang, Wanjun; Pearson, John; Novosad, Valentine; Hoffmann, Axel
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.