Effect of stray-field coupling on active spin-valve elements analyzed by Lorentz transmission electron microscopy

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Abstract
In situ experiments using Lorentztransmission electron microscopy have been performed on 10 μm×30 μm active spin-valve elements through which a current is applied during observation of the magnetization reversal of the sense layer. It is shown that the reversal mechanism and the change in resistance are very different depending on the relative orientations of the easy axis versus the applied field. The results show clearly that the contributions of the magnetostatic fields, due to either ferromagnetic coupling or stray-field coupling, are higher than that of the field induced by the sensing current. A model is proposed to predict the offset of the giant magnetoresistance curves with respect to zero field. This model has been found to be in good agreement with the experimental results.