Magnetoresistance behaviour of magnetostatically coupled Ni80Fe20 wires

Abstract The magnetostatic coupling in lithographically defined 25 nm thick Ni 80 Fe 20 wire arrays has been investigated using magnetoresistance (MR) measurements. The structures consist of array of micron-size wires with inter-wire spacings in the range from 50 nm to 2 μm. For the field applied along the easy axis of the magnetostatically coupled wire array, a novel magnetoresistance behaviour is observed which we explain in terms of anti-parallel alignment of magnetisation in adjacent wires in the array. The MR response to the field applied along the hard axis is found to be very sensitive to the inter-wire spacing due to magnetostatic interactions. Our observations show that magnetostatic coupling is an important parameter in the design of magnetic devices.