MAGNETIC-STRUCTURE OF CR IN EXCHANGE-COUPLED FE CR(001) SUPERLATTICES/

We demonstrate how the noncollinear exchange coupling between the Fe l ayers in Fe/Cr(001) superlattices is caused by a frustrated spiral mod ulation of the Cr moments not observed in bulk. The noncollinear coupl ing vanishes above the Neel temperature of this commensurate antiferro magnetic Cr order. This clarifies the essential contribution of Cr ord ering to the coupling in the regime of smallest thicknesses where no i ncommensurate Cr spin density wave can form. For larger Cr thicknesses we observe a predicted incommensurate to commensurate transition with temperature.