In this paper, we study FePt/NM/FePt//MgO (NM=Pt or Pd) spin valves with perpendicular magnetization deposited by molecular beam epitaxy. Using extraordinary Hall effect and magnetoresistance, we show that the electrodes can be of different coercivities and magnetically decoupled, with current-in-plane magnetoresistances up to 0.8% at room temperature. Finally, using magnetic force microscopy observations, we prove that the different coercivities of the electrodes are controlled by different magnetization reversals and domain-wall pinning, thus allowing the obtaining of an antiparallel state.
International audienceThe magnetization reversal of 10 nm thick FePt nanowires has been studied for widths down to 30 nm. Above 500 nm, the magnetic domains grow within a dendritic structure. Below 300 nm, the reversal takes place by propagation of a single domain wall (DW), and the coercivity increases. Below 50 nm, the coercivity increase is such that a mix of nucleation and DW propagation appears. These results suggest that the reversal process is determined by the comparison of the wire dimensions with four characteristic lengths: the dendrite width, the disorder length, the mean edge roughness, and the nucleation distance
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