Giant magnetocaloric effect and soft-mode magneto-structural phase transition in MnAsJ. D. Zou1, 2, H. Wada3, B. G. Shen1, J. R. Sun1 and W. Li2
1 State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences Beijing 100080, China
2 Functional Materials Research Institute, Central Iron and Steel Research Institute Beijing 100081, China
3 Department of Physics, Kyushu University - Higashi-ku, Fukuoka 812-8581, Japan
received 31 August 2007; accepted in final form 10 December 2007; published February 2008
published online 15 January 2008
Maxwell relation and mean-field approximation are chosen to estimate the total entropy change and the magnetic entropy change, respectively. The experimental results are exactly consonant with the theoretical results. Consequently, the magnetic entropy changes make up the majority of the total entropy change, and the lattice entropy changes are small. The giant magnetocaloric effect in MnAs is clarified. According to thermodynamics discussion, the modulus of compression and the stress at TC decrease dramatically. Therefore, the magneto-structural phase transition in MnAs is a kind of soft mode.
75.30.Sg - Magnetocaloric effect, magnetic cooling.
75.30.Kz - Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.).
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
© EPLA 2008