Currents induced by domain wall motion in thin ferromagnetic wires

Abstract

Historically the role of eddy currents in the motion of Bloch walls has been extensively studied. In contrast the direct interaction of currents with such a moving wall has received very little attention. However recently it has been shown that a wall can be displaced by the effects of a current alone, a fact which is important to the development of spintronics. We report here that such a moving wall within an itinerant ferromagnet constitutes a seat of electro-motive-force (or more accurately a spin-motive-force) which induces a current flow in an external circuit. While an external magnetic field is the most evident means by which to induce Bloch wall motion, it is not the only possibility and the forces intrinsic to certain geometries imply that the state of a spintronics memory device might be read via this mechanism using currents alone and that power amplification of spin polarized pulses is possible. An estimate of the induced current shows it to be technologically useful.