Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 42: Thin films – anisotropy

MA 42.7: Vortrag

Donnerstag, 15. März 2018, 11:15–11:30, EB 301

Origin of defect induced magnetism in TiO₂ anatase probed with X-ray magnetic circular dichroism — •Markus Stiller¹, José Barzola-Quiquia¹, Pablo D. Esquinazi¹, Alpha T. N’Diaye², Hendrik Ohldag³, Thomas Lautenschläger⁴, and Daniel Spemann⁴ — ¹Abteilung für Supraleitung und Magnetismus, Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnestr. 5, D-04103, Germany — ²Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States — ³SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California, 94025 USA — ⁴Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstraße 15, 04318 Leipzig, Germany

The temperature and field dependence of the magnetization of epitaxial, polycrystalline undoped TiO₂ anatase thin films on LaAlO₃ and SrTiO₃ substrates was investigated. Field hysteresis as well as zero-field cooled and field cooled curves were measured for the as-prepared thin films as well as after irradiation with low energy (200 eV) argon ions. The irradiated anatase thin films show an increased magnetic moment and exhibit ferromagnetism at room temperature, with an easy axis parallel to the c-axis, i.e. an out-of-plane magnetization. The anisotropy depends on film orientation, phase and surface roughness as well as the energy used for defect production. XMCD measurements show that the spin polarized band is at the titanium edge, not at the O 2p band edge, at the thin film surface.