Magnetic field and temperature-induced first-order transition in Gd 5(Si 1.5Ge 2.5): a study of the electrical resistance behavior

Abstract

Magnetic field (0–4 T) and temperature dependencies (4.2–320 K) of the electrical resistance of Gd 5(Si 1.5Ge 2.5), which undergoes a reversible first-order ferromagnetic↔paramagnetic phase transition, have been measured. The electrical resistance of Gd 5(Si 1.5Ge 2.5) 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 ∼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 ∼25% discontinuity at 198 K. The isothermal magnetic field dependence of the electrical resistance from 212⩽ T⩽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(Si 1.5Ge 2.5) 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 ∼2 T, and the isofield temperature gap between critical magnetic fields is ∼7 K.