SKM 2021 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 5: Posters Magnetism II
MA 5.23: Poster
Dienstag, 28. September 2021, 10:00–13:00, P
Cation- and lattice-site-selective magnetic depth profiles of ultrathin Fe3O4(001) films — Tobias Pohlmann1,2, •Timo Kuschel3, Jari Rodewald1, Jannis Thien1, Kevin Ruwisch1, Florian Bertram2, Eugen Weschke4, Padraic Shafer5, Joachim Wollschläger1, and Karsten Küpper1 — 1Uni Osnabrück, Germany — 2DESY, Hamburg, Germany — 3Uni Bielefeld, Germany — 4HZB Bessy II, Berlin, Germany — 5ALS, Berkeley, USA
We present x-ray magnetic circular dichroism (XMCD) and x-ray resonant magnetic reflectivity (XRMR) measurements on ultrathin Fe3O4(001) films to obtain magnetic depth profiles of the different cation species Feoct2+, Fetet3+, and Feoct3+ located on octahedral and tetrahedral sites of the inverse spinel structure of Fe3O4. Performing XRMR on the three resonant XMCD energies yields magnetic depth profiles that each correspond to one specific cation species.
The depth profiles of both Fe3+ cations reveal a (3.9±1.0)-Å-thick surface layer of enhanced magnetization, which is likely due to an excess of these ions at the expense of the Feoct2+ species in the surface region. The magnetically enhanced Fetet3+ layer is additionally shifted about 2.9±0.4 Å farther from the surface than the Feoct3+ layer [1].
Moreover, we compare the depth profiles with the recently revealed cation vacancy reconstruction of the Fe3O4(001) surface [2] as well as the unreconstructed Fe3O4(111) surface that is Feoct-terminated [3].
[1] T. Pohlmann et al., Phys. Rev. B 102, 220411(R) (2020)
[2] R. Bliem et al., Science 346, 1215 (2014)
[3] S. Brück et al., Appl. Phys. Lett. 100, 081603 (2012)