Room Temperature Magnetocaloric Effect in ${\hbox {La}}_{0.7}{\hbox {Sr}}_{0.3}{\hbox {Mn}}_{1\hbox {-}{\rm x}}{\hbox {Co}}_{\rm x}{\hbox {O}}_{3}$

We have investigated the magnetic properties and magnetocaloric effect in La_0.7Sr_0.3Mn_1-xCo_xO₃ prepared by a conventional solid-state reaction method. Magnetic measurements versus temperature revealed that the Curie temperature (T_C) decreased gradually with increasing Co content (x); T_C values are about 360, 310, 296 and 280 K for x =0.0, 0.06, 0.08 and 0.1, respectively. Magnetic entropy change (ΔS_m) of the samples under a magnetic field change of 10 kOe was calculated by using isothermal magnetization data. We have found its maximum (|ΔS_max|) achieved around T_C, which is not changed much (~ 1.5 J·kg^-1·K^-1) with increasing Co-doping concentration. If combining the samples with x = 0.06, 0.08 and 0.10 for magnetic refrigeration, particularly, the temperature range can be used in between 266 K and 322 K, where |ΔS_max| values are stable at about 0.98 J·kg^-1·K^-1. The relative cooling power is accordingly about 55 J·kg^-1 and comparable to that of other magnetocaloric alloys. These results suggest La_0.7Sr_0.3Mn_1-xCo_xO₃ compounds to be a potential candidate for magnetic refrigerators at room temperature.