Magnetic properties of Gd 5(Si 1.5Ge 2.5) near the temperature and magnetic field induced first order phase transition

Abstract

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(Si 1.5Ge 2.5) have been studied. The temperature and/or magnetic field induced magnetic phase transition in Gd 5(Si 1.5Ge 2.5) is a first order ferromagnet↔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 ∼0.36 K/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(Si 1.5Ge 2.5) 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(Si 1.5Ge 2.5) specimen where the magnetically ordered (ferromagnetic) and disordered (paramagnetic) phases co-exist.