Influence of A-site cation disorder on structural and magnetocaloric properties of Nd0.7–xLaxSr0.3MnO3 (x=0.0, 0.1, 0.2 & 0.3)

Abstract

In the present research, the influence of A-site ionic size disorder on structural, magnetic and magnetocaloric properties of Nd0.7–xLaxSr0.3MnO3 (for x=0.0, 0.1, 0.2 & 0.3) compounds were investigated. These compounds were synthesized by solid state reaction route and crystallized in orthorhombic structure with Pnma space group. An average ionic radius <rA> increased with La-substitution which influenced the physical properties such as the magnetic entropy varying from 4.78 J/kg·K (for x=0.0) to 3.55 J/kg·K (for x=0.3) and the maximum magnetization at 5 K changing from 3.92 μB (for x=0.0) to 3.59 μB (for x=0.3). The change in maximum magnetic entropy decreased with increase of A-site average ionic radius. The decrease in magnetic entropy indicated the suppression of lattice disorder that influenced the spin-lattice coupling. The ferromagnetic transition temperature shifted toward room temperature with La substitution. As <rA> increased, the phase transition changed from first order (for x=0.0) to second order (for x≥ 0.1) and the refrigeration capacity increased to a significant level. The modest change in magnetic entropy over a wide range of transition temperature might be useful for future active magnetic refrigeration technology.