Nonlinear dynamics of spin-injected magnons in magnetic nanostructures

It has recently been proposed that spin waves can be critically excited in a very thin unbounded single magnetic metal film by a bounded spin-polarized dc current. Here it is shown that, beyond threshold, the interaction between the driven modes may lead to high-frequency oscillatory instabilities and universal chaotic phenomena. Numerical solutions are presented for the resulting equations of motion that describe the dynamics of two coupled modes in a spin-injection field, showing cascades of period-doubling bifurcations, intermittency, and the breakup of a two torus, for a realistic set of phenomenological parameters. © 2002 American Institute of Physics.