Spin-transfer torque based damping control of parametrically excited spin waves in a magnetic insulator

• Published in: arXiv.org 2015-08
• Main Authors: Lauer, V, Bozhko, D A, Brächer, T, Pirro, P, Vasyuchka, V I, Serga, A A, Jungfleisch, M B, Agrawal, M, Kobljanskyj, Yu V, Melkov, G A, Dubs, C, Hillebrands, B, Chumak, A V
• Format: Article
• Language: English
• Subjects: Damping; Direct current; Electron spin; Hall effect; Light scattering; Magnons; Polarity; Spintronics; Torque; Yttrium; Yttrium-iron garnet
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1508.07517

The damping of spin waves parametrically excited in the magnetic insulator Yttrium Iron Garnet (YIG) is controlled by a dc current passed through an adjacent normal-metal film. The experiment is performed on a macroscopically sized YIG(100nm)/Pt(10nm) bilayer of 4x2 mm^2 lateral dimensions. The spin-wave relaxation frequency is determined via the threshold of the parametric instability measured by Brillouin light scattering (BLS) spectroscopy. The application of a dc current to the Pt film leads to the formation of a spin-polarized electron current normal to the film plane due to the spin Hall effect (SHE). This spin current exerts a spin transfer torque (STT) in the YIG film and, thus, changes the spin-wave damping. Depending on the polarity of the applied dc current with respect to the magnetization direction, the damping can be increased or decreased. The magnitude of its variation is proportional to the applied current. A variation in the relaxation frequency of +/-7.5% is achieved for an applied dc current density of 5*10^10 A/m^2.