Magneto-elastic coupling in La(Fe, Mn, Si)13Hy within the Bean-Rodbell model

Henrique Neves Bez, Kaspar Kirstein Nielsen, Poul Norby, Anders Smith, Christian R. H. Bahl

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Abstract

First order magnetic phase transition materials present a large magnetocaloric effect around the transition temperature, where these materials usually undergo a large volume or structural change. This may lead to some challenges for applications, as the material may break apart during field change, due to high internal stresses. A promising magnetocaloric material is La(Fe, Mn, Si)13Hy, where the transition temperature can be controlled through the Mn amount. In this work we use XRD measurements to evaluate the temperature dependence of the unit cell volume with a varying Mn amount. The system is modelled using the Bean-Rodbell model, which is based on the assumption that the spin-lattice coupling depends linearly on the unit cell volume. This coupling is defined by the model parameter η, where for η > 1 the material undergoes a first order transition and for η ≤ 1 a second order transition. We superimpose a Gaussian distribution of the transition temperature with a standard deviation σT, in order to model the chemical inhomogeneity. Good agreement is obtained between measurements and model with values of η ∼ 1.8 and σ(T) = 1.0 K. 
Original languageEnglish
Article number056217
JournalA I P Advances
Volume6
Issue number5
Number of pages7
ISSN2158-3226
DOIs
Publication statusPublished - 2016

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© 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

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