GMR spin valve with alternating in-plane and out-of-plane magnetic anisotropy

Abstract

A new type of spin valve (SV) structure consisting of ferromagnetic layers, with the in-plane ( F ‖) and out-of-plane ( F ⊥) anisotropy, separated by a non-magnetic spacer is proposed. We have chosen thin Co layers, sandwiched between Au ones, as those with perpendicular anisotropy. Our measurements have proved that the Co layers show perpendicular anisotropy for 0.4 < t Co < 1.2 nm and in-plane anisotropy for t Co > 1.8 nm. As ferromagnetic layers with the in-plane anisotropy ( F ‖), we have applied either Ni–Fe (1 ≤ t NiFe ≤ 4 nm) or Co ( t Co = 3.2 nm) layers. For both types of structures, i.e., the multilayers [NiFe/Au/Co ⊥/Au] N and [Co ‖/Au/Co ⊥/Au] N , where N is number of repetitions, deposited by the magnetron sputtering, the GMR effect of up to 9% at room temperature is accompanied by a linear and almost non-hysteretic R( H) dependence. GMR is resistant to annealing up to T A ≤ 525 K.