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Title: Critical behavior and magnetocaloric effect of Pr{sub 1−x}Ca{sub x}MnO{sub 3}

The critical behavior of Pr{sub 1−x}Ca{sub x}MnO{sub 3} 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{sub C}  ≈ 118 K, β = 0.351 ± 0.003, γ = 1.372 ± 0.002, and δ = 4.90 ± 0.02 for x = 0.25; T{sub 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{sub 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{sub C} of Pr{sub 1−x}Ca{sub x}MnO{sub 3} compounds, magnetic-entropy change reaches the maximum values of about 5.0, 4.1, and 2.5 J kg{sup −1} K{sup −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{sub max}) obey a power law |ΔS{sub max}(H)|more » ∝ H{sup n}, where exponent values n = 0.68–0.74 are close to those obtained from the theoretical relation n = 1 + (β − 1)/(β + γ)« less
Authors:
; ;  [1] ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
  2. (Viet Nam)
  3. Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093-0411 (United States)
  4. Institute of Chemistry, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Hanoi (Viet Nam)
  5. Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, 144 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
  6. Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology, Hanoi University of Science and Technology, 01 Dai Co Viet, Hai Ba Trung, Hanoi (Viet Nam)
Publication Date:
OSTI Identifier:
22410058
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CALCIUM COMPOUNDS; CONCENTRATION RATIO; ENTROPY; FERROMAGNETISM; HEISENBERG MODEL; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; MANGANATES; MEAN-FIELD THEORY; PARAMAGNETISM; PHASE TRANSFORMATIONS; PRASEODYMIUM COMPOUNDS