THE MAGNETIC-STRUCTURE OF HOLMIUM ERBIUM SUPERLATTICES/

The effect of competing crystal-field anisotropies on magnetic order h as been investigated in a series of Ho/Er superlattices using neutron and resonant X-ray magnetic diffraction techniques. The neutron diffra ction reveals that for temperatures in the interval T-N(Er) less than or equal to T less than or equal to T-N(Ho) the Ho basal-plane order p ropagates coherently through the paramagnetic Er, and that below T-N(E r) the longitudinal component of the Er moments fail to order across t he Ho block. The magnetic superlattice peaks observed in the X-ray sca ttering display an anomalous energy dependence: a sharp resonance is f ound at L(III)(Ho), with no resonance visible at L(III)(Er). These res ults are discussed with reference to models of exchange in metallic su perlattices.