Positive and negative magnetoresistances in Co/Cu/Ni spin-valves

Abstract We studied the magnetoresistance effects in Co/Cu/Ni spin-valves with magnetic fields along different in-plane directions. When the magnetic easy axis directions of Co and Ni layers are parallel, only typical positive magnetoresistance effects were discovered. Interestingly, a magnetoresistance sign inverse was discovered in the spin-valve with different magnetic easy axis directions between Co and Ni layers. This anomalous behavior may be related to the multi-step magnetization reversal processes in these materials.