  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.
