Magnetotransport and domain structures in nanoscale NiFe/Cu/Co spin valve

The spin-valve structures consisting of NiFe(10 nm)/Co(1 nm)/Cu(13 nm)/Co(10 nm)/NiFe(2 nm) with size down to 70 nm×1 μm were fabricated and characterized. When the multilayer bar width was less than 200 nm, the formation of single domain was found. As the pattern width decreased, the switching fields for both the hard layer and the soft layer increased. The fluctuation of switching field in the spin-valve structures was observed. The spin valve patterned by lift off had a much smaller switching field than that patterned by ion milling, which may be caused by edge roughness.