Adiabatic temperature change at first-order magnetic phase transitions: Ni2.19 Mn0.81 Ga as a case study

V. V. Khovaylo, K. P. Skokov, Yu S. Koshkid'Ko, V. V. Koledov, V. G. Shavrov, V. D. Buchelnikov, S. V. Taskaev, H. Miki, T. Takagi, A. N. Vasiliev

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56 Citations (Scopus)

Abstract

A comprehensive study of the adiabatic temperature change Δ Tad in the vicinity of a first-order magnetostructural phase transition has been carried out on a Ni2.19 Mn0.81 Ga Heusler alloy. It was found that the directly measured Δ Tad ∼K is of order of magnitude smaller than that expected from reported in the literature isothermal magnetic entropy change and specific-heat data. A new feature of the adiabatic temperature change in materials with giant magnetocaloric effect, specifically an irreversible character of Δ Tad when the sample is subjected to repeatable action of magnetic field at a constant temperature, has been observed. This effect has been attributed to the irreversible magnetic-field-induced structural transformation. It has been shown that the small value of Δ Tad in Ni2.19 Mn0.81 Ga is not due to the kinetics of the transformation but originates from other factors which are intrinsic to first-order magnetic phase transitions. Relevance of these factors to other giant magnetocaloric materials has been outlined.

Original languageEnglish
Article number060403
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume78
Issue number6
DOIs
Publication statusPublished - 2008 Aug 14

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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