Eur. Phys. J. B 68, 67-72 (2009)
https://doi.org/10.1140/epjb/e2009-00083-9

Investigation of the first-order metamagnetic transitions and the colossal magnetocaloric effect using a Landau expansion applied to MnAs compound

¹ Divisão de Metrologia de Materiais (DIMAT), Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO), 25250-020, Duque de Caxias, RJ, Brasil
² Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, Unicamp, 13083-970, Campinas, SP, Brasil
³ Instituto de Física, Universidade do Estado do Rio de Janeiro (UERJ), 20550-013, Rio de Janeiro, RJ, Brasil

Corresponding author: ^a amcarvalho@inmetro.gov.br

Received: 12 November 2008
Revised: 8 January 2009
Published online: 6 March 2009

Abstract

We have explored a simple Landau model to calculate magnetization isotherms considering magnetic hysteresis. The model parameters have been chosen to fit the magnetic and magnetocaloric data of MnAs compound. Experimental data show that there is a great difference between the isothermal variation of the entropy (S_T) obtained from isotherms measured increasing and decreasing magnetic field. This great difference is reproduced theoretically. From the experimental and phenomenological isotherms, we calculated the S_T. From the theoretical entropy, we also obtained S_T, which does not present the colossal peak.