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Normal and Inverse Current-induced Magnetization Switching

We observed normal and inverse current-induced magnetization switching in single-crystalline nanopillars prepared from Fe(14 nm)/Cr(0.9 nm)/Fe(10 nm)/Ag(6 nm)/Fe(2 nm) multilayers. The nanopillars have a diameter of 150 nm. The central Fe layer is coupled to the thick one by interlayer exchange coupling over Cr, while the topmost Fe layer is decoupled. The opposite spin scattering asymmetries of the Fe/Cr and Fe/Ag interfaces lead to normal and inverse CIMS for the two subsystems, which are combined in a single device. At high magnetic fields, step-like resistance changes are measured at positive currents and are attributed to current-driven magnetic excitations.

Figure: At -20mT, we observe hysteretic magnetization switching at both current polarities, which is related to the opposite spin scattering asymmetries of the Fe/Cr and Fe/Ag interface, respectively. Fe/Ag exhibits normal switching behaviour, whereas for Fe/Cr the direction of the spin-transfer torques is reversed giving rise to inverse switching. At -1166 mT both switching event are suppressed.

H. Dassow, R. Lehndoff, D. E. Bürgler, M. Buchmeier, P. A. Grünberg, C. M. Schneider, and A. van der Hart
Normal and inverse current-induced magnetization switching in a single nanopillar
Appl. Phys. Lett. 89, 222511, (2006).