Direction dependent giant magnetoresistance of spin valves using epitaxial Cr2O3 as the pinning layer

Abstract We report the direction dependent magnetization and the giant magnetoresistance (GMR) data for the spin valves NiFe/Cu/NiFe/Cr 2 O 3 . The sample with the (1 1¯ 0 2) Cr 2 O 3 showed typical spin valve properties after the magnetic field annealing (MFA) parallel to the [1¯ 1 1] direction; the exchange bias of ∼ 7 0 0 Oe and the highly asymmetric GMR effect of ∼ 4 % with the magnetic field sweep. However, the MFA perpendicular to the [1¯ 1 1] direction induced a symmetric GMR effect of ∼ 2.6 % without exchange bias. It is noticeable that the interface exchange coupling constant J by the (1 1¯ 0 2) Cr 2 O 3 is maximally ∼ 0.27 erg / cm 2 . On the other hand, the sample with the (1 0 1¯ 0) Cr 2 O 3 showed no exchange bias in all directions but it displayed a symmetric GMR effect of 1.8–3.5% which was caused by a coercivity difference between two NiFe layers.