Magnetic properties of Gd5(Si1.5Ge2.5) near the temperature and magnetic field induced first order phase transition

The temperature (from 5 to 300 K) and DC magnetic field (from 0 to 90 kOe) dependencies of the DC magnetization and magnetic susceptibility, and the temperature (from 5 to 350 K) dependency of the AC magnetic susceptibility of Gd-5(Si1.5Ge2.5) have been studied. The temperature and/or magnetic field Induced magnetic phase transition in Gd-5(Si1.5Ge2.5) is a first order ferromagnet tt paramagnet transition. The temperature of the magnetic transition in low AC magnetic field is 206 and 217 K for cooling and heating, respectively. The DC magnetic field increases the transition temperature by similar to0.36K/kOe indicating that the paramagnetic phase can be reversibly transformed into the ferromagnetic phase. When the magnetic field is removed, the ferromagnetic phase transforms into the paramagnetic phase showing a large remanence-free hysteresis. The magnetic phase diagram based on the isothermal magnetic field dependence of the DC magnetization at various temperatures for Gd-5(Si1.5Ge2.5) is proposed. The magnetic field dependence of the magnetization in the vicinity of the first order phase transition shows evidence for the formation of a magnetically heterogeneous system in the volume of Gd-5(Si1.5Ge2.5) specimen where the magnetically ordered (ferromagnetic) and disordered (paramagnetic) phases co-exist. (C) 2001 Elsevier Science B.V. All rights reserved.