Magnetization switching behavior in nanostructured NiFe/Co/Cu/Co spin-valve

The evaporated NiFe/Co/Cu/Co spin-valve strips to the 0.2 mu m width were successfully fabricated by the Ar ion-milling through the negative type resist mask exposed by electron beam lithography, which is the simple fabrication method free from the deposition process limitation and multilayer materials. The size effect on the magnetization switching behavior was investigated by measuring the magnetoresistance (MR) change in the nanostructured. strips with various widths on the same glass substrate. The Barkhausen like jump, which suggests the irreversible switching of the micro-domain, was observed in the 0.3 mu m strip in the MR hysteresis. A quite different switching behavior was observed in the 0.2 mu m width strip, which presented the drastically steep switching within 5 Oe in both magnetic layers and demonstrated the well defined quantization of the magnetization direction along the longitudinal direction.