Landau model evaluation of the magnetic entropy change in magnetocaloric materials

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:529

Article

van Dijk, N. H.¹ 

[1] Delft Univ Technol, Fundamental Aspects Mat & Energy Grp, Dept Radiat Sci & Technol, Mekelweg 15, NL-2629 JB Delft, Netherlands

关键词: Landau model;    Magnetocaloric materials;    First-order magnetic transition;    Second-order magnetic transition;   

DOI  :  10.1016/j.jmmm.2021.167871

来源: Elsevier

【 摘 要 】

The field exponent for the magnetic entropy change n = dln(vertical bar Delta S vertical bar)/dln(H) in a magnetic field was evaluated using the Landau model to provide a classification for the nature of the ferromagnetic-to-paramagnetic transitions at the Curie temperature T-C in magnetocaloric materials. The magnetic phase transition can be classified as a first-order magnetic transition (FOMT), a second-order magnetic transition (SOMT) or a critical point (CP) at the border between the first and second order transitions. The value of n is mapped as a function of the reduced temperature and the reduced magnetic field for the FOMT, SOMT and CP. The influence of the magnetic field on the transition temperature was found to be relatively weak for the SOMT and corresponds to a power law for the CP and FOMT.

【 授权许可】

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