Effect of Spin Current on Uniform Ferromagnetism Domain Nucleation.pdf

Accepted for publication in Physical Review Letters. Effect of Spin Current on Uniform Ferromagnetism: Domain Nucleation Junya Shibata Frontier Research System (FRS), The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan 5 CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama, Japan 0 0 2 Gen Tatara PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama, Japan n Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan a J Hiroshi Kohno 6 Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan ] (Dated: February 2, 2008) l l a Large spin current applied to a uniform ferromagnet leads to a spin-wave instability as pointed h out recently. In this paper, it is shown that such spin-wave instability is absent in a state containing - a domain wall, which indicates that nucleation of magnetic domains occurs above a certain critical s spin current. This scenario is supported also by an explicit energy comparison of the two states e m under spin current. t. PACS numbers: 72.25.Ba, 75.40.Gb a m Magnetization dynamics driven by spin torque from a term as the “Doppler shift” [10], where v (∝ j ) rep- -