Anisotropic roughness effects of magnetoresistive hysteresis in scratched NiO spin valves

Magnetoresistance (MR), exchange biasing, and coercivity of NiO/NiFe/Cu/NiFe spin valves, deposited over etched glass, scratched glass, and Si(3)N(4) buffer layers were measured in order to investigate the effect of roughness slope and anisotropic roughness at the NiO/NiFe interface. It was found that the MR ratio and the biasing field were not influenced by etching and scratching the substrate. This was due to a constant value of the average slope of roughness, despite an increased rms roughness. In the case of samples with Si(3)N(4) buffer layer, the MR ratio and exchange biasing field increased due to an increasing slope or roughness. The coercive held of the unbiased NiFe layer was reduced by perpendicular scratching. This was probably due to refinement of the magnetic domains. (C) 1999 Elsevier Science B.V. All rights reserved.