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- Title
Reducing Thermal Hysteresis in Epitaxial Ni–Mn–Ga–Co Films by Transformation Cycling.
- Authors
Diestel, Anett; Chekhonin, Paul; Niemann, Robert; Skrotzki, Werner; Nielsch, Kornelius; Fähler, Sebastian
- Abstract
Films are of particular interest for magnetocaloric refrigeration as they allow for a fast heat exchange. Here we report on metamagnetic epitaxial Ni–Mn–Ga–Co films, where a reduction of thermal hysteresis to 50% during several tens of temperature cycles is observed. This reduction occurs by an increase of the martensitic start temperature and thus can be attributed to a facilitated nucleation of martensite. Two mechanisms for reduction of hysteresis are identified: 1) delamination, which reduces constraints from the rigid substrate and 2) the formation of defects, which reduces the nucleation barrier. The detailed analysis and interpretation of microstructure before and after cycling gives a detailed understanding of the nucleation and delamination process.
- Subjects
HYSTERESIS; METALLIC films; NICKEL-manganese alloys; MAGNETOCALORIC effects; HEAT exchangers
- Publication
Physica Status Solidi (B), 2018, Vol 255, Issue 2, p1
- ISSN
0370-1972
- Publication type
Article
- DOI
10.1002/pssb.201700330