  We investigated magnetic and magnetocaloric properties in Sm1-xSrxMnO3 (x =
0.30-0.5). We report a magnetic field driven first-order metamagnetic
transition in the paramagnetic state in x = 0.4 and 0.5 and a second-order
transition in x = 0.3. The highest magnetic entropy (-Sm = 6.2 J/kgK for H = 5
T at T = 125 K) that occurs in x = 0.4 is associated with the metamagnetic
transition resulting from the field-induced growth and coalescence of
ferromagnetic nano clusters preexisting in the paramagnetic state. Our results
suggest that manganites with intrinsic nanoscale phase separation can be
exploited for magnetic refrigeration.
