Regensburg 2013 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 59: Computational Materials Modelling - Phase Stability III
MM 59.5: Talk
Thursday, March 14, 2013, 16:45–17:00, H24
Improving the magneto-caloric effect in layered alloys: an ab-initio investigation — •Biswanath Dutta1, Tilmann Hickel1, Jörg Neugebauer1, and Andreas Hütten2 — 1Max-Planck-Institut für Eisenforschung GmbH, D-40237, Düsseldorf, Germany — 2Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, PB 100131, 33501 Bielefeld, Germany
The study of magnetocaloric effect (MCE) based magnetic refrigeration is primarily focused on increasing the magnetic entropy difference ΔSmag(H,T) between the two phases across the coupled magnetic and structural transition. Here, we demonstrate a novel strategy consisting of alternating layers of different magnetocaloric materials. For this study, we choose Heusler alloys Ni-Mn-Sn and Ni-Mn-Ga for which the details of MCE in the bulk phase are well investigated. The presence of different chemical species across the interface in the layered structure, however, opens up the possibility of significant changes in the magnetic and structural properties which we investigate with the help of density functional theory. Our calculations reveal that the atomic magnetic moments get modified near the interface leading to the conclusion that interfaces could influence the transition temperatures and the entropy change and thus alter the MCE. In order to further clarify this influence, we carefully investigated strain contributions, interlayer diffusion and possible segregation effects near the interface.