Journal of Experimental and Theoretical Physics

, Volume 108, Issue 2, pp 279–285

Entropy and magnetocaloric effects in ferromagnets undergoing first- and second-order magnetic phase transitions

Order, Disorder, and Phase Transition in Condensed Systems

DOI: 10.1134/S1063776109020101

Cite this article as:
Valiev, É.Z. J. Exp. Theor. Phys. (2009) 108: 279. doi:10.1134/S1063776109020101

Abstract

The exchange striction model is invoked to derive an expression for the entropy of ferromagnetic materials undergoing first- and second-order magnetic phase transitions. The magnetocaloric and barocaloric effects are calculated for the ferromagnet La(Fe0.88Si0.12)13 undergoing a first-order phase transition. The calculated results are in fair agreement with experimental data. The ferromagnet La(Fe0.88Si0.12)13 is used as an example to predict the changes in magnetic and magnetocaloric properties associated with gradual increase in the magnetoelastic coupling constant (i.e., with passage from first- to second-order magnetic transition region). It is shown that stronger magnetoelastic coupling leads to stronger magnetocaloric effects and changes their dependence on magnetic field and pressure. Expressions are obtained for the maximum field- and pressure-induced entropy changes. An analysis is presented of the mechanism responsible for the increase in magnetocaloric and barocaloric effects associated with change from the second- to first-order magnetic phase transition.

PACS numbers

75.30.Sg75.30.Kz

Copyright information

© Pleiades Publishing, Ltd. 2009

Authors and Affiliations

  1. 1.Institute of Metal Physics, Ural DivisionRussian Academy of SciencesYekaterinburgRussia