期刊
JOURNAL OF PHYSICS-CONDENSED MATTER
卷 26, 期 28, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0953-8984/26/28/286001
关键词
magnetic transitions; magnetocaloric effect; critical phenomena
资金
- US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-07ER46438]
- DOE [DE-FG02-06ER46275]
- NSF [DMR-1206278]
- Regional Government of Andalucia
- Spanish Ministry of Science and Innovation
- EU FEDER [MAT 2010-20537]
- PAI of the Regional Government of Andalucia [P10-FQM-6462]
- United States Office of Naval Research [N00014-11-1-0311]
- Converging Research Center Program though the Ministry of Science, ICT and Future Planning, Korea [2013K000405]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1206278] Funding Source: National Science Foundation
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 Pr0.5Sr0.5MnO3, which undergoes a second-order paramagnetic to ferromagnetic (PM-FM) transition at T-C similar to 247 K, and a first-order ferromagnetic to antiferromagnetic (FM-AFM) transition at T-N similar to 165 K. We find that around the second-order PM-FM transition, the MCE (as represented by the magnetic entropy change, Delta S-M) can be precisely determined from magnetization measurements using the Maxwell relation. However, around the first-order FM-AFM transition, values of Delta S-M 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 field-and temperature-dependent magnetization M(T, H) curves, and hence the Delta S-M(T, H) 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 T-C, but a noticeable discrepancy is present for T<
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