Theory of magnetodynamics induced by spin torque in perpendicularly magnetized thin films.
A nonlinear model of spin-wave excitation using a point contact in a thin ferromagnetic film is introduced. Large-amplitude magnetic solitary waves are computed, which help explain recent spin-torque experiments. Numerical simulations of the fully nonlinear model predict excitation frequencies in excess of 0.2 THz for contact diameters smaller than 6 nm. Simulations also predict a saturation and redshift of the frequency at currents large enough to invert the magnetization under the point contact. The theory is approximated by a cubic complex Ginzburg-Landau type equation. The mode's nonlinear frequency shift is found by use of perturbation techniques, whose results agree with those of direct numerical simulations.
Hoefer
M A
MA
Department of Applied Mathematics, University of Colorado, Boulder, 80309-0526, USA. hoefer@colorado.edu
Ablowitz
M J
MJ
Ilan
B
B
Pufall
M R
MR
Silva
T J
TJ