Nonlinear excitations in CsNiF 3 in magnetic fields perpendicular to the easy plane

Centre de Recherche en Physique du Solide, De ´partement de Physique, Universite de Sherbrooke, Que´bec, Canada J1K 2R1~Received 9 September 2003; revised manuscript received 19 December 2003; published 6 May 2004!Experimental and numerical studies of the magnetic-field dependence of the specific heat and magnetizationof single crystals of CsNiF