Magnetic behavior and phase diagram of Gd4(Co1−xCux)3 compounds

Abstract

In order to study the effects caused by substituting Co for Cu on the magnetic properties of Gd4(Co1−xCux)3 compounds with x=0.05, 0.1, 0.2, and 0.3, superconducting quantum interference device magnetization measurements were performed on polycrystalline samples in the temperature range of 5–300 K using applied magnetic fields from 0 to 5 T. Experimental results show that the substitution of Co for Cu produces an increase in magnetic anisotropy, which is accompanied by important changes in the magnetic ordering of these ferrimagnetic compounds with respect to that of Gd4Co3. A magnetic T-x phase diagram comprised of c-axis, canted, and possibly partially disordered ferrimagnetic phases, is proposed. The calculated average saturation magnetic moment of Co atoms decreases exponentially with increasing Cu content. Such behavior of MCo(x) may originate from the combined effect of the 3d band filling by 4s electrons from Cu atoms and a strong dependence of Co moment on the number of local Co neighboring atoms.