Magnetocaloric effect of perovskite manganites La0.7□0.1Ca0.2MnO3

- La0.7□0.1Ca0.2MnO3 compound is crystallized in an orthorhombic symmetry with Pnma space group.
- A strong correlation between electrical and magnetic properties in La0.7□0.1Ca0.2MnO3 compounds.
- Theoretical work on magnetocaloric effect using the phenomenological model in La0.7□0.1Ca0.2MnO3 was investigated.
- The results of calculation are in a good agreement with the experimental results.

The magnetocaloric properties of the polycrystalline manganites La0.7□0.1Ca0.2MnO3 based on magnetic and resistivity measurements were investigated. Firstly, the equation ΔS=-α∫0HδLn(ρ)δTHdH relates magnetic order to the transport behavior of the compounds. The relation between ρ and M was found to maintain the form of ρ=ρ0exp(-M/α) for temperatures near and slightly below TC. This result reveals the important effect of magnetic polarons on the transport properties. It is obvious that magnetic disorder, characterized by ΔSM, affects the magnetic polarons, while the latter influence the electronic transport properties, which may be the underlying reason for the salient ΔSM-ρ relation. On the other hand, based on a phenomenological model, the value of the magnetocaloric effect has been determined from the calculation of magnetization as a function of temperature under different magnetic fields M (T, H). This study also provides an alternative method to determine magnetic entropy change on the basis of magnetic and resistivity measurements.