Magnetic field and temperature-induced first-order transition in Gd-5(Si1.5Ge2.5): a study of the electrical resistance behavior

Magnetic field (0-4 T) and temperature dependencies (4.2-320 K) of the elec trical resistance of Gd-5(Si1.5Ge2.5), which undergoes a reversible first-o rder ferromagnetic<->paramagnetic phase transition, have been measured. The electrical resistance of Gd-5(Si1.5Ge2.5) indicates that the magnetic phas e transition can be induced by both temperature and magnetic field. The tem perature dependence of the electrical resistance, R(T), for heating at low temperatures in the zero magnetic field has the usual metallic character, b ut at a critical temperature of T-cr = 216 K the resistance shows a similar to 20% negative discontinuity due to the transition from the low-temperatu re high-resistance state to the high-temperature low-resistance state. The R(T) dependence for cooling shows a similar but positive similar to 25% dis continuity at 198 K. The isothermal magnetic field dependence of the electr ical resistance from 212 less than or equal to T less than or equal to 224 K indicates the presence of temperature-dependent critical magnetic fields which can reversibly transform the paramagnetic phase into the ferromagneti c phase and vice versa. The critical magnetic fields diagram determined fro m the isothermal magnetic field dependencies of the electrical resistance o f Gd-5(Si1.5Ge2.5) shows that the FM<->PM transition in zero magnetic field on cooling and heating occurs at 206 and 213 K, respectively. The full iso thermal magnetic filed hysteresis for the FM<->PM transition is similar to 2 T, and the isofield temperature gap between critical magnetic fields is s imilar to 7 K. (C) 2000 Elsevier Science B.V. All rights reserved.