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
_0.7
Sr
_0.3
Mn
_1-x
Co
_x
O
₃
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
_0.7
Sr
_0.3
Mn
_1-x
Co
_x
O
₃
compounds to be a potential candidate for magnetic refrigerators at room temperature.