ON THE MAGNETIC-STRUCTURE OF ACTINIDE MONOPNICTIDES

The magnetic structures of the actinides (i.e. those materials contain ing 5 (f) under bar electrons) exhibit considerable complexity. The re asons for this are a competition between exchange, often anisotropic i n nature, crystal-held, and quadrupolar mteractions. Based on work on compounds of the lanthanides (4 (f) under bar electrons), we have well -developed mechanisms for understanding magnetic structures. The probl em in the actinides is compounded by our inability to quantify the ind ividual interactions. The reason for this difficulty is the hybridizat ion that often occurs between the 5 (f) under bar electrons surroundin g the actinide with both the conduction electrons and those of the sur rounding atoms. To simplify this paper we shall discuss only one set o f magnetic structures, those of the actinide monopnictides. These have received perhaps the most attention of any series, and exemplify the complexities and challenges of this held; one to which Jean Rossat-Mig nod made seminal contributions.