Emission of spin waves by a magnetic multilayer traversed by a current

TLDR

Spin-wave–electron interactions are strongly enhanced at normal–ferromagnetic interfaces in metallic thin films, raising local Gilbert damping and making the system analogous to an injection laser. A dc current across the interface induces stimulated spin-wave emission, and above a critical density the damping turns negative, causing spontaneous magnetization precession and generating a dc voltage analogous to the Josephson effect. © 1996 The American Physical Society.

Abstract

The interaction between spin waves and itinerant electrons is considerably enhanced in the vicinity of an interface between normal and ferromagnetic layers in metallic thin films. This leads to a local increase of the Gilbert damping parameter which characterizes spin dynamics. When a dc current crosses this interface, stimulated emission of spin waves is predicted to take place. Beyond a certain critical current density, the spin damping becomes negative; a spontaneous precession of the magnetization is predicted to arise. This is the magnetic analog of the injection laser. An extra dc voltage appears across the interface, given by an expression similar to that for the Josephson voltage across a superconducting junction. \textcopyright{} 1996 The American Physical Society.