LARGE MAGNETOSTRICTION AND COMPLEX PHASE-TRANSITION IN UNISN

In high magnetic fields, magnetostriction in UNiSn is found to be rema rkably enhanced with a sharp peak at a temperature T-Q higher than the antiferromagnetic transition temperature T-N. The pronounced volume r eduction in magnetic fields below T-Q suggests that the lattice deform ation results from ferro-quadrupolar ordering of 5f-electron orbits. T he competition between magnetic ordering and lattice instability is es sential for the complex phase transition in UNiSn at 43 K. (C) 1998 Pu blished by Elsevier Science B.V. All rights reserved.