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Magnetization reversal in nanoscale (Sm-Co)/Fe (hard/soft) bilayer exchange-spring magnets with inplane uniaxial magnetic anisotropy was investigated by magnetometry, conversion-electron Mössbauer spectroscopy (CEMS) and atomistic Fe spin-structure calculations. Magnetization loops along the easy direction exhibit signatures typical of exchange-spring magnets. In-field CEMS at inclined γ-ray incidence onto thin (2-nm) 57 electrons. The coupling at the hard/soft interface is described by the uniaxial exchange-anisotropy field, h int , as a parameter. Our calculated R 23 ratios as a function of the (reduced) applied field, h, exhibit similar features as observed in the experiment, in particular a minimum at (h min , R min ). R min is found to increase with h int , thus providing a measure of the interface coupling. Evidence is provided for the existence of fluctuations of the interface coupling. The calculations also show that the Fe-spin spiral formed during reversal is highly inhomogeneous. In general, our simulation of the Fe spin structure is applicable for the interpretation of experimental results on layered exchange-spring magnets.

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