Short-range magnetic order in holmium-praseodymium superlattices

The chemical and magnetic structures of Ho/Pr superlattices have been studied by a combination of X-ray and neutron scattering techniques. While the Ho blocks are HCP, the Pr blocks retain their bulk-like DHCP structure, but with a stacking of the hexagonal atomic planes that is not coherent between successive blocks. Below a Neel temperature of approximately 110 K, the Ho magnetic moments order into a basal plane spiral with a magnetic coherence length that is limited to the width of a single Ho block, even for a sample comprising of only six atomic planes of Pr. These observations are discussed in terms of the differing band structures of the two elements.