Large magnetocaloric effect in a La0.7Ca0.3MnO3 single crystal

We report the results of a thorough study of the magnetocaloric effect (MCE) in a La0.7Ca0.3MnO3 single crystal, which undergoes a first-order magnetic phase transition at similar to227 K. The magnetic entropy change DeltaS(M) and the adiabatic temperature change DeltaT(ad) reach, respectively, similar to6.42 J/kg K and 4.76 K for DeltaB=5 T and even if both are smaller than those exhibited by gadolinium (similar to9.8 J/kg K and similar to11.7 K), the DeltaS(M) distribution here is much more uniform than that of gadolinium and polycrystalline manganites. This is desirable for an Ericson-cycle magnetic refrigerator. The MCE is larger in the single-crystalline manganite compared to the polycrystalline one. The manganite single crystal has large DeltaS(M) induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials. All these make the lanthanum manganite single crystal an attractive candidate as a working substance for AMR. The molecular field model provides a fairly good description of the magnetic entropy change at temperatures close to the Curie temperature. (C) 2004 American Institute of Physics.