Magnetocaloric effect and critical behavior in Pr0.5Sr 0.5MnO3: An analysis of the validity of the Maxwell relation and the nature of the phase transitions

R. Caballero-Flores, N. S. Bingham, M. H. Phan, M. A. Torija, C. Leighton, V. Franco, A. Conde, T. L. Phan, S. C. Yu, H. Srikanth

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Abstract

The Maxwell relation, the Clausius-Clapeyron equation, and a non-iterative method to obtain the critical exponents have been used to characterize the magnetocaloric effect (MCE) and the nature of the phase transitions in Pr 0.5Sr0.5MnO3, which undergoes a second-order paramagnetic to ferromagnetic (PM-FM) transition at , and a first-order ferromagnetic to antiferromagnetic (FM-AFM) transition at . We find that around the second-order PM-FM transition, the MCE (as represented by the magnetic entropy change, ΔSM) can be precisely determined from magnetization measurements using the Maxwell relation. However, around the first-order FM-AFM transition, values of ΔSM calculated with the Maxwell relation deviate significantly from those calculated by the Clausius-Clapeyron equation at the magnetic field and temperature ranges where a conversion between the AFM and FM phases occurs. A detailed analysis of the critical exponents of the second-order PM-FM transition allows us to correlate the short-range type magnetic interactions with the MCE. Using the Arrott-Noakes equation of state with the appropriate values of the critical exponents, the eld- and temperature-dependent magnetization curves, and hence the curves, have been simulated and compared with experimental data. A good agreement between the experimental and simulated data has been found in the vicinity of the Curie temperature TC, but a noticeable discrepancy is present for . This discrepancy arises mainly from the coexistence of AFM and FM phases and the presence of ferromagnetic clusters in the AFM matrix.

Original languageEnglish (US)
Article number286001
JournalJournal of Physics Condensed Matter
Volume26
Issue number28
DOIs
StatePublished - Jun 16 2014

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