Magnetic field and temperature-induced first-order transition in Gd5(Si1.5Ge2.5):: a study of the electrical resistance behavior

Magnetic field (0-4 T) and temperature dependencies (4.2-320 K) of the electrical resistance of Gd-5(Si1.5Ge2.5), which undergoes a reversible first-order ferromagnetic<->paramagnetic phase transition, have been measured. The electrical resistance of Gd-5(Si1.5Ge2.5) indicates that the magnetic phase transition can be induced by both temperature and magnetic field. The temperature dependence of the electrical resistance, R(T), for heating at low temperatures in the zero magnetic field has the usual metallic character, but 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-temperature high-resistance state to the high-temperature low-resistance state. The R(T) dependence for cooling shows a similar but positive similar to 25% discontinuity at 198 K. The isothermal magnetic field dependence of the electrical 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 ferromagnetic phase and vice versa. The critical magnetic fields diagram determined from the isothermal magnetic field dependencies of the electrical resistance of 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 isothermal magnetic filed hysteresis for the FM<->PM transition is similar to 2 T, and the isofield temperature gap between critical magnetic fields is similar to 7 K. (C) 2000 Elsevier Science B.V. All rights reserved.