Generation of dc voltages by a magnetic multilayer undergoing ferromagnetic resonance

Abstract

We predict that a dc voltage $V$ appears across a magnetic multilayer undergoing ferromagnetic resonance. The voltage exists along a direction perpendicular to the layer plane. This is the magnetic analog of a photovoltaic cell. We calculate the rate of spin flip of conduction-electron spins, induced by the precession of the magnetization. Also, we solve the Valet-Fert spin-diffusion equation in the various layers. The dc voltage $V$ is obtained by combining these two equations. For sufficiently large precession amplitude, $V$ converges toward a fixed value of order $\ensuremath{\simeq}\ensuremath{\Elzxh}\ensuremath{\omega}/e\ensuremath{\simeq}10\ensuremath{\mu}\mathrm{V},$ where \ensuremath{\omega} is the angular frequency of precession and e the electron charge.