Relation Between Magnetic Entropy and Resistivity in La{sub}0.67Ca{sub}0.33MnO{sub}3

摘要

We present an investigation of the magnetic en tropy △S and resistivity ρ, and the relation between them, for La{sub}0.67Ca{sub}0.33MnO{sub}3 film. We found that the maximum △S is approximately 6 J/kg·K, and the maximum magnetoresistance (defined as ρ(0)/ρ(H) - 1) is about 400 under a field μ{sub}oH of 5 T. A careful analysis gives an equation of the form △S = -α∫δln(ρ)/δT{sub}HdH (a = 21.74 emu/g)(H from 0 to H), which relates magnetic order to transport behavior of the compounds. This result reveals the predominant role of magnetic polarons on the magnetoresistive property of manganites. It also provides an alternative method to determine magnetic entropy change on the basis of resistive measurements.