Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 53: Magnetic Heuslers, half-metals and oxides

MA 53.3: Vortrag

Freitag, 5. April 2019, 10:00–10:15, H33

In-situ spin polarized time-of-flight momentum microscopy of the Heusler alloy films Co₂MnGa(001), Co₂MnSi(001), and Co₂Fe_0.4Mn_0.6Si(001) — •Sergey Chernov¹, Christian Lidig¹, Olena Fedchenko¹, Katerina Medjanik¹, Dmitry Vasilyev¹, Sergey Babenkov¹, Martin Jourdan¹, Jürgen Braun², Hubert Ebert², Gerd Schönhense¹, and Hans-Joachim Elmers¹ — ¹Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany — ²Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany

Half-metallic ferromagnets are an important class of materials as they provide fully spin polarized conduction electrons that may be exploited by spintronic devices. Although first-principles calculations predict many half-metallic Heusler alloys, only a few have been experimentally proven[1]. Theoretical studies indicate that local electron correlations in Heusler compounds are often significant and surface states play a dominant role. We have measured spin polarized electronic dispersions in the valence band region up to 1.5 eV binding energy using spin polarized time-of-flight k-microscopy and photoexcitation by the 4^th harmonic of a Ti-sapphire laser (6 eV). The comparison of spin-integrated photoemission spectra obtained with exitation at 6 eV and in the hard X-ray regime allows one to discriminate surface related from bulk states. This allows for a thorough test of theoretical models, indicating the need to extend the single particle approach to include many-body effects. [1] M. Jourdan et al., Nat. Commun. 5, 3974 (2014)