Element-specific magnetization reversal in Fe/Ce multilayers: a study by X-ray magnetic circular dichroism and the magneto-optic Kerr effect

Fe/Ce multilayers are magnetically soft with coercive fields of a few Oerst eds. In this artificial system, the itinerant 5d electrons of Ce are magnet ically polarized by hybridization with the spin-split 3d states of Fe. To o btain an insight into the magnetization reversal process, the element selec tivity of X-ray magnetic circular dichroism was used to measure the magneti zation of the Ce-Sd electrons as a function of an applied magnetic field. C omparison with the magnetization curves studied by the magneto-optic Kerr e ffect, which averages over the whole system, revealed that the coercivity i n the hysteresis of the ordered Ce-Sd moments is reduced by 50%. We propose that this is an effect of the magnetically disturbed interface or of the c omplex non-collinear magnetic structure of the Ce layers detected by recent experiments of X-ray resonant magnetic scattering. The results are compare d to the X-ray dichroic and Kerr hysteresis loops of the multilayers Fe/La/ Ce/La and Fe/CeH2-delta. These systems are magnetically harder and their co ercivities are identical. (C) 2000 Elsevier Science B.V. All rights reserve d.