Solid State and Materials

The European Physical Journal B

, Volume 68, Issue 1, pp 67-72

First online:

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

  • A. Magnus G. CarvalhoAffiliated withDivisão de Metrologia de Materiais (DIMAT), Instituto Nacional de Metrologia Email author 
  • , A. A. CoelhoAffiliated withInstituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas
  • , S. GamaAffiliated withInstituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas
  • , F. C.G. GandraAffiliated withInstituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas
  • , P. J. von RankeAffiliated withInstituto de Física, Universidade do Estado do Rio de Janeiro (UERJ)
  • , N. A. de OliveiraAffiliated withInstituto de Física, Universidade do Estado do Rio de Janeiro (UERJ)

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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 (ST) obtained from isotherms measured increasing and decreasing magnetic field. This great difference is reproduced theoretically. From the experimental and phenomenological isotherms, we calculated the ST. From the theoretical entropy, we also obtained ST, which does not present the colossal peak.

PACS

75.30.Sg Magnetocaloric effect, magnetic cooling 75.20.En Metals and alloys 75.10.-b General theory and models of magnetic ordering