On the Optimization of Magneto-Volume Coupling for Practical Applied Field Magnetic Refrigeration
authors Davarpanah, A; Belo, JH; Amaral, VS; Amaral, JS
nationality International
journal PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
author keywords Bean-Rodbell; entropy change; magneto-volume coupling; second order phase transition
keywords PHASE-TRANSITION; 1ST-ORDER; HYSTERESIS
abstract Materials with strong magneto-volume coupling can present a coupled first-order magnetic and structural transition and a giant magnetocaloric effect. The trade-off of the resulting increased entropy change is hysteresis, and incomplete transition when the applied field is <2 T, implying that the full cooling capacity of the refrigerant is not harnessed. In this work, the behavior of the magnetic entropy change as a function of temperature is simulated, considering the Bean-Rodbell model, for various spin systems with Curie temperatures close to room temperature. Increasing magneto-volume coupling parameter (eta) results in higher entropy change peak value (Delta S-M(max)), together with a narrowing of entropy change function Delta S-M(T), limiting the working temperature range. Accordingly, cooling capacity behaves non-monotonously, reaching a peak value at eta(MAX), which departs from the tri-critical point as H increases up to 2 T. By tuning eta, the cooling capacity can be considerably larger than the uncoupled system (up to 15-40% for low applied fields). Such tuning can be accomplished experimentally through proper chemical substitution. A universal behavior of cooling capacity as a function of eta(MAX) underlines that the performance of magnetic refrigerant is optimized, by tuning magneto-volume coupling within the second order range, rather than the tri-critical region.
publisher WILEY-V C H VERLAG GMBH
issn 0370-1972
year published 2019
volume 256
issue 3
digital object identifier (doi) 10.1002/pssb.201800419
web of science category Physics, Condensed Matter
subject category Physics
unique article identifier WOS:000461236600025
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journal analysis (jcr 2017):
journal impact factor 1.729
5 year journal impact factor 1.568
category normalized journal impact factor percentile 38.060
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