On the free layer reversal mechanism of FeMn-biased spin-valves with parallel anisotropy

Transmission electron microscopy has been used to investigate the 'free' layer reversal mechanism of a range of FeMn-biased spin-valves with parallel anisotropy. Fresnel imaging enabled three modes of reversal to be directly observed for different in-plane applied field orientations and interlayer coupling strengths. Low-angle diffraction has provided some quantitative information on the level of dispersion involved in the reversals. Comparison with a modified Stoner-Wohlfarth coherent rotation model is made and magnetic modelling of the free layer energy variation as a function of magnetization orientation is presented. This has helped provide a deeper understanding of the observed discrepancies between the model and experimental data. Finally, a qualitative description of the observed domain processes is given in relation to the free layer energy for the corresponding experimental conditions.