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Title: Crossover from first-order to second-order phase transitions and magnetocaloric effect in La{sub 0.7}Ca{sub 0.3}Mn{sub 0.91}Ni{sub 0.09}O{sub 3}

We have prepared La{sub 0.7}Ca{sub 0.3}Mn{sub 0.91}Ni{sub 0.09}O{sub 3} and then studied its critical behavior and magnetocaloric effect. Analyzing temperature and field dependences of magnetization around the ferromagnetic-paramagnetic transition reveals the sample undergoing the second-order magnetic phase transition with the critical parameters T{sub C} ≈ 199.4 K, β = 0.171 ± 0.006, and γ = 0.976 ± 0.012. A considerable difference of these critical exponents compared with those expected for the standard models is due to the sample exhibiting the crossover property (tricriticality); its exponent values are more close to those expected for the tricritical mean-field theory with β = 0.25 and γ = 1. Under the field 40 kOe, the maximum magnetic entropy change (−ΔS{sub max}) around T{sub C} is about 7.1 J·kg{sup −1}·K{sup −1}, corresponding to a refrigerant capacity RC ≈ 170 J/kg. Particularly, its magnetic-field dependence obeys a power law |ΔS{sub max}| ∝ H{sup n}, where n = 0.55 is quite far from the value calculated from the relation n = 1 + (β − 1)/(β + γ)
Authors:
; ;  [1] ;  [1] ;  [2]
  1. Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
  2. (Viet Nam)
Publication Date:
OSTI Identifier:
22273860
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: (c) 2014 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; COMPARATIVE EVALUATIONS; ENTROPY; LANTHANUM COMPOUNDS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; MANGANESE COMPOUNDS; MEAN-FIELD THEORY; NICKELATES; PARAMAGNETISM; PHASE TRANSFORMATIONS; TEMPERATURE DEPENDENCE