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Cite Details

T. A. Ho, T. D. Thanh, Y. Yu, D. M. Tartakovsky, T. O. Ho, P. D. Thang, A.-T. Le, T.-L. Phan and S. C. Yu, "Critical behavior and magnetocaloric effect of Pr1-xCaxMnO3", J. Appl. Phys., vol. 117, no. 17, doi:10.1063/1.4914537, pp. 17D122, 2015

Abstract

The critical behavior of Pr1−xCaxMnO3 samples with x = 0.25, 0.27, and 0.29 has been investigated. Detailed analyses of magnetic-field dependences of magnetization at temperatures around the paramagnetic-ferromagnetic transition, M(H,T), reveal that the samples undergo a second-order magnetic phase transition. The Arrott plot method predicts the values of critical parameters to be TC ≈ 118 K, β = 0.351 0.003, γ = 1.372 0.002, and δ = 4.90 0.02 for x = 0.25; TC ≈ 116 K, β = 0.362 0.002, γ = 1.132 0.004, and δ = 4.09 0.03 for x = 0.27; and TC ≈ 110 K, β = 0.521 0.002, γ = 0.912 0.005, and δ = 2.71 0.02 for x = 0.29. The values of β = 0.351 (for x = 0.25) and β = 0.362 (for x = 0.27) are close to the value β = 0.365 expected for the 3D Heisenberg model, proving an existence of short-range ferromagnetic interactions in these samples. A slight increase in Ca-doping content (x = 0.29) leads to the shift of the β value (= 0.521) towards that of the mean-field theory (with β = 0.5) characteristic of long-range ferromagnetic interactions. The samples also exhibit a magnetocaloric effect: around TC of Pr1−xCaxMnO3 compounds, magnetic-entropy change reaches the maximum values of about 5.0, 4.1, and 2.5 J kg−1 K−1 for x = 0.25, 0.27, and 0.29, respectively, under an applied-field change of 50 kOe. Magnetic-field dependences of the maximum magnetic-entropy change (ΔSmax) obey a power law |ΔSmax(H)| ∝ Hn, where exponent values n = 0.68 − 0.74 are close to those obtained from the theoretical relation n = 1 + (β − 1)/(β + γ).

BibTeX Entry

@article{ho-2015-critical,
author = {T. A. Ho and T. D. Thanh and Y. Yu and D. M. Tartakovsky and T. O. Ho and P. D. Thang and A.-T. Le and T.-L. Phan and S. C. Yu},
title = {Critical behavior and magnetocaloric effect of Pr $_{1-x}$ Ca $_{x}$ MnO $_{3}$ },
year = {2015},
urlpdf = {http://maeresearch.ucsd.edu/Tartakovsky/Papers/ho-2015-critical.pdf},
journal = { J. Appl. Phys.},
volume = {117},
number = {17},
doi = {10.1063/1.4914537},
pages = {17D122}
}