Size effect on NiFe/Cu/NiFe/IrMn spin-valve structure for an array of PHR sensor element

Conventional NiFe/Cu/NiFe/IrMn multilayer spin-valve structure is used for patterning planar Hall effect (PHE) sensor fabrication. The three different junctions, 50 x 50 mu m(2), 20 x 20 mu m(2) and 5 x 5 mu m(2), were prepared by lithography technique for obtaining the PHE profiles. The PHE measurements were carried out for all three junctions using four probe methods. Increased sensitivities are obtained for smaller patterned junctions, while recording a value of 13.45 mu V/Oe being the maximum sensitivity for 5 x 5 mu m(2) junction. The magnetic properties of the spin valves are characterized by vibrating sample magnetometer (VSM) to know the influence of exchange bias field on PHE signal. Structural and compositional aspects were examined by transmission electron microscopy (TEM) and energy dispersive spectrometer (EDX), which revealed that the diffusion of Cu layer into the magnetic layers indirectly helps PHE signal by bringing modifications to the anisotropy and coercivity. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.