Observation of the Fe spin spiral structure in Fe/Sm-Co exchange-spring bilayers by Mossbauer spectroscopy

The in-plane Fe spin spiral structure for Fe/Sm-Co(1 (1) over bar 00) exchange-spring magnetic bilayers was investigated by Fe-57 conversion electron Mossbauer spectroscopy during the magnetization reversal process, and correlated with hysteresis loops measured via the longitudinal magneto-optic Kerr effect. A direct experimental proof for a relaxed spiral angular spin distribution in the Fe layer is presented. Under negative applied fields the interfacial Fe spins rotate by up to 40degrees with respect to the easy axis of the Sm-Co hard-magnet layer.