Simulating device size effects on magnetization pinning mechanisms in spin valves

Abstract

The effects of magnetostatic interactions on the giant magnetoresistive ͑GMR͒ response of NiFe/ Cu/NiFe spin valves are studied using an analytical model. The model is applicable to devices small enough for the magnetic layers to exhibit single-domain behavior. Devices having lengths in the track-width direction of 10 m and interlayer separations of 4.5 nm are studied. Stripe heights are varied from 0.5 to 2 m. The magnetization of one magnetic layer is pinned by a transverse pinning field that is varied from 0 to 24 kA/m ͑300 Oe͒. GMR curves for transverse fields are calculated. At zero external field the magnetization of the layers shows a tendency to align themselves antiparallel in the transverse direction. This results in an offset from the ideal biasing of the device. Broadening of the curves due to shape anisotropy occurs with decreasing stripe height and increasing magnetic layer thickness, and the magnetization in the pinned layer becomes less stable.

Simulated magnetoresistive behavior of geometrically asymmetric spin valves

“…The self-demagnetization of the magnetic layers and interlayer magnetostatic interactions prevents the devices from being perfectly pinned and from being ideally biased [2]. Also indicated on the solid curve of Fig.…”

“…The biasing deteriorates as tp increases, because both the selfdemagnetization of *the pinned layer and interlayer magnetostatic coupling increases. The increased selfdemagnetization results in the canting, at H = 0, of the magnetization of the pinned layer away from its intended direction [2]. Biasing is very poor for the devices of Fig.…”

“…The magnetization of a device is modeled by using a semi-analytical model in which the magnetic layers are treated as single-domain films [2] the model [2].…”

Effect of Substrate Type on Overall Performance of Magnetostrictive Thin Film Cantilever Actuator for MEMS

“…Si is a basic material for micro machining technique and used for many micro applications [1][2][3][4][5][6][7][8]. Nevertheless its high brittle property limits its use for large deformation.…”