SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 37: Magnetic Heuslers

MA 37.3: Vortrag

Donnerstag, 30. März 2023, 10:00–10:15, HSZ 403

Long range ordering in NiCoMnAl magnetic shape memory thin films with martensitic intercalations — •Inga Ennen, Dario Stierl, Laila Bondzio, and Andreas Hütten — Thin Films and Physics of Nanostructures, Physics Department, Bielefeld University, 33615 Bielefeld, Germany

Magnetic shape memory Heusler alloys, like NiMnX (X=Al,Ga,Sn,In), are considered as promising materials for magnetocaloric cooling applications due to their magnetoelastic coupling near room temperature. In order to reduce the thermal hysteresis in NiCoMnAl thin films, the usage of alternating active transforming austenitic and martensitic intercalation layers are beneficial. Therefore, the stoichiometry of these two layers is chosen in such a way that their thermal hysteresis does not overlap. If the austenite active layers have a similar thickness compared to the martensite intercalations a 3D check board pattern becomes visible in HRTEM cross section images. The contrast is due to alternating martensite/austenite domains.

In this contribution we aim for an improved understanding of the 3D check board pattern formation. Therefore, the number of the alternating layers as well as the ratio between the thicknesses of the two different layers have been varied. The phase transition has been characterized by temperature dependent XRD and TEM analysis. Furthermore, freestanding Heusler films have been prepared and analyzed in comparison to the substrate-bounded systems.