Regensburg 2022 – scientific programme
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MA: Fachverband Magnetismus
MA 19: Poster 1
MA 19.12: Poster
Tuesday, September 6, 2022, 17:30–20:00, P2
Chemical Ordering and Phase Transition in all-d-metal Heusler alloy NiCoMnTi — •David Koch1, Benedikt Beckmann1, Olga Miroshkina2, Nuno M. Fortunato1, Markus Gruner2, Hongbin Zhang1, Oliver Gutfleisch1, and Wolfgang Donner1 — 1Institute of Material Science, Technical Univeristy of Darmstadt, 64287 Darmstadt Germany — 2Faculty of Physics and Center of Nanointegration, University of Duisburg-Essen, 47057 Duisburg Germany
Chemical ordering in NiMn-based Heusler alloys with magnetostructural phase transition is crucial for understanding the physics of the phase transition and is known for influencing the properties of the alloys. In the new field of all-d-metal Ni(Co)MnTi Heusler alloys, the experimental determination of chemical order is challenging due to the low difference in scattering power of the different elements. Here we report a combined approach of neutron and x-ray diffraction for an analysis of chemical order in Ni(Co)MnTi alloys and show that no Heusler-typical L21 order between Ti and Mn is present. Furthermore, Co and Ni atoms do not exhibit order among them; however, the martensitic phase transition and Curie temperature of Co containing samples can be shifted signifcantly by changing the degree of B2 order with a proper heat treatment. Using first-principles calculations, we reveal how the structural and magnetic sub-systems depend on the degree of B2 disorder. An outlook to further experiments on single crystals is given.