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Magnetocaloric effect and critical behavior in melt‐extracted Gd 60 Co 15 Al 25 microwires (Phys. Status Solidi A 9∕2015)
Author(s) -
Xing Dawei,
Shen Hongxian,
Jiang Sida,
Liu Jingshun,
Phan ManhHuong,
Wang Huan,
Qin Faxiang,
Chen Dongming,
Liu Yanfen,
Sun Jianfei
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201570459
Subject(s) - magnetic refrigeration , critical exponent , materials science , condensed matter physics , scaling , magnetic field , ferromagnetism , paramagnetism , refrigerant , exponent , thermodynamics , magnetization , phase transition , physics , mathematics , quantum mechanics , linguistics , philosophy , geometry , gas compressor
The images on the inside back cover refer to the article by Dawei Xing et al. (pp. 1905–1910 ). They show the critical behavior for melt‐extracted Gd‐based microwires. The authors investigated Gd 60 Co 15 A l25 wires with an average diameter of 40 μm that underwent a second‐order paramagnetic to ferromagnetic (PM–FM) transition at ∼100 K. A careful analysis of critical exponents near the PM–FM transition was performed. The n value (related to the magnetic state of the specimen) of the investigated wires is ∼0.743 calculated from the magnetic field dependence of the maximum magnetic entropy change (Δ S m ), which deviates from the value of n = 2/3 (∼0.67) based on the mean field approach. The critical exponents of β, γ, and δ for the present wires are obtained by the modified Arrott plots (MAP) method based on the scaling theory and the values are 0.432, 1.244, and 3.351, respectively. All these values also significantly deviate from those obtained according to the mean field theory (β = ∼0.5, y = ∼1, and δ = ∼3). Scaling plots obtained by using the critical exponents and the experimental data demonstrate that the critical exponents obtained for the present microwires are precise and reliable. This study indicates that the Gd 60 Co 15 A l25 microwires are excellent magnetic refrigerants for active magnetic refrigeration in the liquid nitrogen temperature range.