Magnetocaloric effect in Y-doped La0.6Ca0.4MnO3 enhanced by Griffiths phase and re-entrance of first-order phase transition |
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| Affiliation: | 1. Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin, 17035, South Korea;2. Institute of Research and Development, Duy Tan University, 550000, Da Nang, Viet Nam;3. Faculty of Environmental and Natural Sciences, Duy Tan University, 550000, Danang, Viet Nam;4. Phenikaa University Nano Institute (PHENA), PHENIKAA University, Ha Noi, 12116, Viet Nam;5. Department of Physical Chemistry, Plovdiv University “Paisii Hilendarski”, 24, Tzar Asen Str, 4000, Plovdiv, Bulgaria;6. Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980, Dubna, Russia;7. Hubei Engineering Research Center of Weak Magnetic-Field Detection, College of Science, China Three Gorges University, Yichang, 443002, PR China;8. Department of Science Education, Chungbuk National University, Cheongju, 360-763, South Korea |
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| Abstract: | It has been known that bulk La0.6Ca0.4MnO3 is an intermediate material of the first- and second-order characters with the tricritical-point exponents, and the doping of a metal ion in it usually causes a continuous second-order transition. The present work reports the re-entrance of a discontinuous first-order transition in orthorhombic La0.6-xYxCa0.4MnO3 (x = 0.03–0.09) compounds. This enhances the magnetocaloric effect. For the field H = 30 kOe, the maximum magnetic-entropy change (|ΔSmax|) and relative cooling power (RCP) have been evaluated being about 5.45–6.3 J/kg·K and 130–185 J/kg, respectively. If combining these compounds as refrigerant blocks in a rotary ring model, a magnetic cooling device can operate at temperatures T = 85–280 K, with |ΔSmax| ≈ 5.5 J/kg⋅K and RCP ≈ 1073 J/kg. Aside from the re-entranced first-order phase transition, the magnetization and structural analyses have proved the enhanced magnetocaloric effect in La0.6-xYxCa0.4MnO3 related to a Griffiths singularity, and local Jahn-Teller distortions of the perovskite structure (since the Mn3+/Mn4+ ratio and orthorhombic structural phase are unchanged vs. x). |
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| Keywords: | Perovskite manganites Magnetic and magnetoocaloric behaviors Magnetic order |
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