Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.18: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
XRMR study of ultrathin magnetite films on MgO and SrTiO3 substrates — •Tobias Pohlmann1, Karsten Küpper1, Timo Kuschel2, and Joachim Wollschläger1 — 1Osnabrück University, Osnabrück, Germany — 2Bielefeld University, Bielefeld, Germany
Magnetite thin films are frequently discussed as material for spintronic devices, such as magnetic tunnel junctions. For such multilayer devices, understanding the magnetic interface effects can be significantly important.
While x-ray magnetic circular dichroism (XMCD) − the main technique to investigate the magnetic properties in an element resolved fashion − is sensitive to the entire film volume, x-ray magnetic reflectometry (XRMR) allows for the probing of the magnetic moment depth distribution and even of buried interfaces.
Recently, it has been found that the easy axis of magnetite films depends on the substrate, switching from [110] in Fe3O4/MgO(001) to [100] in Fe3O4/SrTiO3(001) [1].
To clarify the origin of this behaviour, we have grown magnetite ultrathin films on MgO(001) and SrTiO3(001) substrates by molecular beam epitaxy. We employ XMCD together with XRMR to obtain magnetic depth profiles of these samples. By selecting the Fe L2,3 resonances, the impact of the subtrate choice on magnetite’s differently coordinated Fe ions can be resolved.
Magnetite’s large saturation moment of 4 µ B /f.u. leads to asymmetry ratios of the XRMR signals as high as 60 % at the resonances, demonstrating the capability of this method for the study of magnetite.
[1] K. Küpper et al., PRB 94, 024401 (2016)