Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)
MA 32.76: Poster
Friday, February 29, 2008, 11:15–14:00, Poster E
Current-induced effects in exchange-biased layers — •Alina M. Deac2,1, Yuichi Otani1, Takekazu Yamane2, Akio Fukushima1, Hitoshi Kubota1, Shinji Yuasa1, and Yoshishige Suzuki1,2 — 1Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan — 2Graduate School of Engineering Science, Osaka University, Osaka, Japan
Exchange-biasing a magnetic layer might improve the peak-shape of microwave signals induced by a spin-polarized current. FM/AFM bi-layers also constitute systems which may provide experimental proof of spin-transfer induced effects in AFM layers. We analyzed spin-transfer effects in two types of pillars: (A) IrMn5/CoFe5/Cu4/CoFe3/IrMn5 and (B) IrMn5/CoFe5/Cu4/CoFe3/Cu3/IrMn5 (thickness in nm) [3]. For structure A, both CoFe layers are pinned; for B, the exchange bias between the top CoFe and IrMn layers is cancelled by inserting the 3 nm Cu layer, so the top CoFe layer is free. The top IrMn layer was kept in B (reference) to insure that the current polarization throughout the pillar remains the same as for A samples, and the measured magnetoresistance is similar. While B pillars exhibit the typical trends of current-induced effects in free layers, the behavior of A samples is consistently different. By applying enough current, both exchanged-biased layers can be switched, partially or completely. Above a given current threshold, these effects become irreversible, indicating that an area of the antiferromagnetic layer has changed orientation. The initial state can be recovered by field re-annealing the samples.