Spin-transfer-induced domain wall motion in a spin valve

We have studied the current-induced displacement of a domain wall (DW) in the permalloy (Py) layer of a Co/Cu/Py spin-valve structure. At zero and very small applied fields (<10 Oe), the displacement is in opposite direction for opposite dc currents, and the current density required to move DW is of the order of a few 106 A/cm2. At higher applied magnetic fields, the DW motion, even though triggered by the current, has its direction controlled by the field.