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Martensitic transition and magnetoresistance in a Cu-Al-Mn shape memory alloy. Influence of aging

Jordi Marcos·Antoni Planes·Lluís Mañosa·Amílcar Labarta·Bart Jan Hattink
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Abstract

We have studied the effect of ageing within the miscibility gap on the electric, magnetic and thermodynamic properties of a non-stoichiometric Heusler Cu-Al-Mn shape-memory alloy, which undergoes a martensitic transition from a $bcc$-based ($β$-phase) towards a close-packed structure ($M$-phase). Negative magnetoresistance which shows an almost linear dependence on the square of magnetization with different slopes in the $M$- and $β$-phases, was observed. This magnetoresistive effect has been associated with the existence of Mn-rich clusters with the Cu$_2$AlMn-structure. The effect of an applied magnetic field on the martensitic transition has also been studied. The entropy change between the $β$- and $M$-phases shows negligible dependence on the magnetic field but it decreases significantly with annealing time within the miscibility gap. Such a decrease is due to the increasing amount of Cu$_2$MnAl-rich domains that do not transform martensitically.

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Jordi Marcos, Antoni Planes, Lluís Mañosa, Amílcar Labarta, Bart Jan Hattink. 2002-07-10. Martensitic transition and magnetoresistance in a Cu-Al-Mn shape memory alloy. Influence of aging. https://doi.org/10.1103/physrevb.66.054428

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