The influence of crystal electrical field on first- and second-order magnetic phase transition in Praseodymium intermetallics

In order to investigate the influence of crystal electrical field on determining the first- or second-order ferromagnetic-paramagnetic phase transition, we have considered Praseodymium intermetallics systems PrX2 (X = Al,Ni,Rh,Ru,Mg), Using a theoretical model which takes into account the crystal field and exchange interaction, we have studied in analytical form the Landau free energy as a function of the model parameters, that leads to a phase diagram, which permits to show that the existence of first- or second-order magnetic phase transitions is strongly related to the magnitude of crystal field and critical temperature. (C) 1998 Elsevier Science B.V. All rights reserved.