Significant enhancement of magnetocaloric effect in a NiMnCuGa Heusler alloy through textural modification

Magnetocaloric materials are of increasing interest to bring magnetic refrigeration to everyday households and drastically impact the energy demands for temperature control devices. In this work, a polycrystalline Heusler alloy of composition Ni2Mn0.76Cu0.24Ga with coinciding structural and magnetic...

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Bibliographic Details
Published in:Journal of applied physics 2020-06, Vol.127 (22)
Main Authors: McLeod, M. V., Bayer, D., Turgut, Z., Giri, A. K., Majumdar, B. S.
Format: Article
Language:English
Subjects:
Applied physics
Compressive properties
Ferromagnetism
Heusler alloys
Households
Magnetic fields
Magnetic materials
Magnetic properties
Magnetism
Magnetization
Martensite
Martensitic transformations
Neutron diffraction
Preferred orientation
Refrigeration
Sharpening
Temperature control
Thermal cycling
Transformation temperature
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Summary:Magnetocaloric materials are of increasing interest to bring magnetic refrigeration to everyday households and drastically impact the energy demands for temperature control devices. In this work, a polycrystalline Heusler alloy of composition Ni2Mn0.76Cu0.24Ga with coinciding structural and magnetic transformation temperatures was subjected to compressive stress assisted thermal cycling (SATC) to enhance the magnetic properties by inducing a preferred orientation in the martensite. Isofield magnetization measurements showed a sharpening of the transformation between ferromagnetic martensite and paramagnetic austenite due to SATC. In isothermal magnetization measurements, SATC was seen to increase the magnetostructural coupling. With a 2 T applied magnetic field, the magnetocaloric effect (MCE) increased from ∼10 to ∼25 J/kg K and the refrigeration capacity (RC) almost doubled due to SATC. Heat capacity measurements were largely unaffected by SATC. The change in adiabatic temperature was estimated by using Cp and change in magnetic entropy (ΔSM) calculations. SATC was seen to increase ΔTad from ∼1.2 K to 2 K for an applied magnetic field of 2 T. Neutron diffraction measurements revealed highly textured martensite in the as received state that rotated to a more ideal preferred orientation after SATC that enhanced the magnetostructural transformation; and thus, improving the MCE and ΔTad.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0003366