2003/09/11 by M. D. Stiles, Jiang Xiao, Andrew Zangwill +1 · 1 citation
Materials Science · Physics and Astronomy · #Angular momentum #Anisotropy #Classical mechanics #Condensed matter physics #Instability #Larmor precession #Magnetic Properties and Applications #Magnetic field #Magnetic properties of thin films #Magnetization #Mechanics #Physics #Precession #Quantum mechanics #ZnO doping and properties #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.69.054408
Submitted to Physical Review B
arxiv created 2003/09/11 · openalex publication_date 2004/02/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We solve appropriate drift-diffusion and Landau-Lifshitz-Gilbert equations to demonstrate that unpolarized current flow from a nonmagnet into a ferromagnet can produce a precession-type instability of the magnetization. The fundamental origin of the instability is the difference in conductivity between majority spins and minority spins in the ferromagnet. This leads to spin accumulation and spin currents that carry angular momentum across the interface. The component of this angular momentum perpendicular to the magnetization drives precessional motion that is opposed by Gilbert damping. Neglecting magnetic anisotropy and magnetostatics, our approximate analytic and exact numerical solutions using realistic values for the material parameters show (for both semi-infinite and thin-film geometries) that a linear instability occurs when both the current density and the excitation wave vector parallel to the interface are neither too small nor too large. For many aspects of the problem, the variation of the magnetization in the direction of the current flows makes an important contribution.