Field-driven structural phase transition and sign-switching magnetocaloric effect in Ni–Mn–Sn

Date
2007-09-26
Authors
Lograsso, Thomas
Pasquale, M.
Schlagel, Deborah
Sasso, C.
Giudici, L.
Lograsso, Thomas
Schlagel, Deborah
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Ames Laboratory
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Abstract

Depending on the starting equilibrium temperature, the application of a magnetic field on a sample of Ni–Mn–Sn produces sample heating or cooling during adiabatic experiments. The competition between endothermal and exothermal effects is observed close to the martensite-to-austenite magnetostructural phase transition. A model assuming the coexistence of two phases and a field dependence of their volume allows to compute the evolution of entropy and heat capacity during the phase transition. The correct fitting of the results suggests that the field-induced reduction of the martensite-to-austenite transition temperature is responsible for the observed sign switching of the magnetocaloric effect.

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<p>The following article appeared in <em>Applied Physics Letters</em> 91 (2007): 131904 and may be found at h<a href="http://dx.doi.org/10.1063/1.2790829" target="_blank">ttp://dx.doi.org/10.1063/1.2790829</a>.</p>
Keywords
entropy, magnetocaloric effects, manganese alloys, martensitic transformations, nickel alloys, solid-state phase transformations, tin alloys
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