Local domain structure of exchange-coupled NiFe∕CoO nanowire probed by nonlocal spin valve measurement

Abstract

We investigate the local magnetization process in a 100-nm-wide Permalloy/CoO exchange-coupled wire by means of nonlocal spin valve measurements for a structure with lateral geometry. The domain structure in the exchange-coupled wire is found to change with the direction of the exchange bias. When the exchange bias is parallel to the easy axis of the Permalloy wire, the magnetization-reversal process can be expressed by the single domain model. However, when the exchange bias is perpendicular to the easy axis, the magnetization reversal is accompanied by domain nucleation and annihilation processes even in the lateral dimension of 100nm. The reason for the dependence of the domain structure on the direction of the exchange bias is discussed.