SIMULATING DEVICE SIZE EFFECTS ON MAGNETIZATION PINNING MECHANISMS INSPIN VALVES

The effects of magnetostatic interactions on the giant magnetoresistiv e (GMR) response of NiFe/Cu/NiFe spin valves are studied using an anal ytical model. The model is applicable to devices small enough for the magnetic layers to exhibit single-domain behavior. Devices having leng ths in the track-width direction of 10 mu m and interlayer separations of 4.5 nm are studied. Stripe heights are varied from 0.5 to 2 mu m. The magnetization of one magnetic layer is pinned by a transverse pinn ing field that is varied from 0 to 24 kA/m (300 Oe). GMR curves for tr ansverse fields are calculated. At zero external field the magnetizati on of the layers shows a tendency to align themselves antiparallel in the transverse direction. This results in an offset from the ideal bia sing of the device. Broadening of the curves due to shape anisotropy o ccurs with decreasing stripe height and increasing magnetic layer thic kness, and the magnetization in the pinned layer becomes less stable. (C) 1996 American Institute of Physics.