Piezoelectric enhancement of giant magnetoresistance in spin-valves with different magnetic anisotropies

Abstract

The phenomenon of giant magnetoresistance (GMR) in spin-valves under applied magnetic field is well established. We present piezoelectric control of the GMR ratio at room temperature for standard multilayered spin-valve structure fabricated on (011)-Pb (Mg1/3Nb2/3)O3-PbTiO 3 (PMN-PT) piezoelectric substrate. Four samples namely, S 1, S2, S3, and S4 were, respectively, fabricated such that the magnetic easy axis makes an initial angle of 0°, 30°, 45°, and 60° with magnetic field applied during measurement. For S1, the GMR ratio decreases under electric field whereas it increases for the samples making progressively larger initial magnetization angles with the external field. We suggest that for S1, magnetic alignment between the two magnetic layers decreases due to the rotation of bottom free layer magnetization resulting in the decrease of antiparallel resistance as well as the GMR ratio under applied electric field whereas for the other samples, the antiparallel resistance increases due to improvement in antiparallel alignment between the two magnetic layers causing increase in the GMR ratio at room temperature. Our results establish new way to control and even enhance the magnetoresistance via converse piezoelectric effect in spin-valves with different magnetic anisotropies. © 2013 American Institute of Physics.