PRESSURE EFFECTS ON MAGNETISM IN THE URANIUM AND NEPTUNIUM MONOPNICTIDES

The magnetic properties of the cubic NaCl uranium and neptunium monopn ictides (UX, NpX; X=N, P, As, Sb, Pi) have been widely studied at ambi ent pressure. Properties ranging from itinerant to localized magnetism , and a variety of ordered magnetic structures have been observed. In particular the profusion of non-collinear double-k or triple-k structu res is a consequence of strongly anisotropic exchange interactions. Th e application of pressure is a clean way of continuously varying the l attice parameter, and the exchange interactions, from one compound to another. A number of studies have been performed using different high pressure techniques. Some of the effects of pressure can be understood in a simple picture of a continuous variation of the lattice paramete r, but some highly anomalous effects are also found which are discusse d in relation to the possible nature of the magnetic interactions. (C) 1998 Elsevier Science S.A.