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MA: Fachverband Magnetismus

MA 57: Posters Magnetism II

MA 57.48: Poster

Donnerstag, 19. März 2020, 15:00–18:00, P3

Determination of the bulk spin polarization of Fe₃O₄ (111) thin films by means of spin-resolved hard X-ray time-of-flight microscopy — •Matthias Schmitt¹, Ozan Kirilmaz¹, Sergey Chernov², Sergey Babenkov², Dmitry Vasilyev², Katerina Medjanik², Olena Fedchenko², Yuri Matveyev³, Andrei Gloskowski³, Christoph Schlueter³, Hans-Joachim Elmers², Gerd Schönhense², Michael Sing¹, and Ralph Claessen¹ — ¹Universität Würzburg, Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, 97074 Würzburg, Germany — ²Universität Mainz, Institut für Physik, 55128 Mainz, Germany — ³DESY Photon Science, 22607 Hamburg, Germany

The electronic structure of ferrimagnetic magnetite Fe₃O₄ has previously been studied by spin-resolved soft X-ray photoemission [1,2]. However, the theoretically predicted spin polarization of -100% at the Fermi level [3] has never been experimentally shown. We have studied 30 nm thick Fe₃O₄ (111) films on ZnO(0001) using spin-resolved hard X-ray photoemission (beamline P22, PETRA III, Hamburg) with a ToF microscope [4] and a novel 3D spin detector. Benefitting from the large probing depth at photon energies of up to 5 keV surface effects like a magnetically dead layer, lowering the measured spin polarization, are negligible. We thus have been able to measure the true bulk spin polarization and discuss our findings as derived from the complex analysis of the microscopy data. [1] Phys. Rev. B 65, 064417 (2002); [2] J. Phys.: Condens. Matter 19, 315218 (2007); [3] J. Phys. Soc. Jpn. 68, 1607 (1999); [4] J. Synchr. Rad. 26, 1996 (2019)