Influence of La addition on the structural, magnetic and magnetocaloric properties in Sr2−xLaxFeMoO6 (0≤x≤0.3) double perovskite

We report the effect of carrier doping via partial substitution of La3+ for Sr2+ on the structural, magnetic and magnetocaloric properties of Sr2FeMoO6 double perovskite. Polycrystalline Sr2−xLaxFeMoO6 (x=0.0, 0.1, 0.2, 0.3) samples were prepared using the conventional solid state reaction method. Using the X-ray diffraction (XRD) analysis it was established that all the samples crystallized in a tetragonal structure with I4/mmm space group. An increase in the La doping lead to an increase in the lattice parameter ‘a’ and the volume of the unit cell. The lattice parameter ‘c’ however remained unchanged. The temperature variation in magnetization and Arrott analysis suggested a second order of ferromagnetic phase transition in all samples with Curie temperature, TC increasing from 358 K for x=0.0–365 K for x=0.3. A gradual increase in magnetization was also observed with the increasing La content up to x=0.2. The magnetic entropy change was calculated from the measurement of isothermal magnetization versus magnetic field at different temperatures. The tunability of magnetization and TC simply by adjusting the concentration of La and synthesis conditions makes Sr2FeMoO6 an attractive material for magnetic refrigeration at desired temperature.