Mark Hoefer - Waves in Nanomagnets

Waves in Nanomagnets

Mark Hoefer
N.I.S.T., Boulder, CO

The recently discovered spin transfer effect enables the application of localized torques in magnetic thin film nanostructures. In the point contact geometry, this effect can result in large amplitude spin wave generation. The well studied Slonczewski model of spin torque in trilayer nanostructures is the Landau-Lifshitz equation modified with a local spin torque term. In this talk, a non-local model of point contacts in single layer thin magnetic films is presented and studied numerically in two spatial dimensions. Here, the spin torque term in the Landau-Lifshitz equation is non-local and is due to spin diffusion effects. A variety of quasi-periodic mode solutions to this equation are found including localized standing waves, vortex spiral waves, and a weakly diffracting collimated beam of spin waves, the direction of which can be steered by changing the direction of an applied magnetic field. Mode selection is explained using linear spin wave theory.