VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2022-12-02T03:25:18ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2016-07-06T06:36:05Z2016-07-06T06:36:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1798This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/17982016-07-06T06:36:05ZCritical behavior and magnetocaloric effect of Pr1-xCaxMnO3The critical behavior of Pr1− x Ca x MnO3 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 T C ≈ 118 K, β = 0.351 ± 0.003, γ = 1.372 ± 0.002, and δ = 4.90 ± 0.02 for x = 0.25; T C ≈ 116 K, β = 0.362 ± 0.002, γ = 1.132 ± 0.004, and δ = 4.09 ± 0.03 for x = 0.27; and T C ≈ 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 T C of Pr1− x Ca x MnO3 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 (ΔS max) obey a power law |ΔS max(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).
T. A. Ho1, T. D. Thanh1,2, Yu3, D. M. , T. O. Ho4, P. D. Thang5, Anh-Tuan Le6, The-Long Phan1 and S. C. YuA. Ho T.D. Thanh T.Yikyung YuM. Tartakovsky3 D.O. Ho T.Duc Thang Phampdthang@vnu.edu.vnAnh Tuan LeThe Long PhanC. Yu S.