Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 25: Magnetic Heusler Compounds

MA 25.8: Vortrag

Mittwoch, 13. März 2013, 11:15–11:30, H10

NMR Sheds Light on Structural Evolution upon Annealing and Off-Stoichiometry in Nominal Co₂MnSi Thin Films — •Steven Rodan¹, Alexey Alfonsov¹, Maria-Eleni Belesi¹, Filippo Ferraro², Jürgen T. Kohlhepp², Henk J. M. Swagten², Bert Koopmans², Bernd Büchner¹, and Sabine Wurmehl¹ — ¹Leibniz Institute for Solid State and Materials Research, 01171 Dresden, Germany — ²Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands

Half-metallic ferromagnets (HMFs), with fully spin-polarized conduction electrons, are prime candidates for developing spintronic devices. Many Heusler compounds, such as Co₂MnSi, are predicted to be HMFs. A local probe technique such as nuclear magnetic resonance (NMR) is essential for understanding the microscopic origin of manifested physical properties, such as the magnetoresistance ratio measured in giant magnetoresistance (GMR) devices. Using NMR we have studied the evolution of local atomic structure in numerous Co₂MnSi thin films prepared by different methods, subjected to various annealing temperatures, and with varying stoichiometry. For all cases, we investigated models for different types of disorder, and quantitatively deduced the off-stoichiometry. By understanding how the local structure affects the physical properties, one can hope to control and optimize the properties which are of interest for spintronics by appropriately tuning the structure.