Title:
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Anomalies related to the TA2 phonon mode condensation in the Heusler Ni2MnGa alloy
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Author:
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Mañosa, Lluís; Gonzàlez Comas, Alfons; Obradó Llauradó, Eduard; Planes Vila, Antoni; Chernenko, V. A.; Kokorin, V. V.; Cesari, Eduard
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Other authors:
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Universitat de Barcelona |
Abstract:
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We present specific-heat, elastic constants, and magnetic susceptibility measurements in a ferromagnetic
Ni
2
MnGa Heusler alloy, in a temperature range where partial condensation of the [110]
TA
2
phonon at q=0.33, accompanied by the development of a micromodulated structure has been reported to occur. All these quantities have been found to exhibit anomalous behavior at the temperature of condensation. From the results presented, it can be concluded that the appearance of the micromodulated structure takes place via a phase transition which is very weakly first order. It is found that at the transition point there is a significant reduction of the dynamical stability of the lattice not just for the transverse phonon at q=0.33, but also for any shear long wavelength distortion. It is particularly remarkable the large softening of C′ (around 60%) at the transition point. Finally, it is also shown that the intermediate transition is related to a magnetoelastic interaction. |
Subject(s):
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-Materials magnètics -Propietats magnètiques -Transformacions martensítiques -Magnetic materials -Magnetic properties -Martensitic transformations |
Rights:
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(c) The American Physical Society, 1997
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Document type:
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Article Article - Published version |
Published by:
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The American Physical Society
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