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O: Fachverband Oberflächenphysik

O 89: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth I

O 89.6: Talk

Thursday, March 15, 2018, 11:45–12:00, MA 041

Strain and ordering effects of ultrathin epitaxial ferrite films on SrTiO₃(001) — •Jari Rodewald, Tabea Nordmann, and Joachim Wollschläger — Fachbereich Physik, Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany

Ultrathin epitaxial ferrite films as NiFe₂O₄ or CoFe₂O₄ are in the focus of spintronics since both materials are insulating and ferrimagnetic. Thus, they are well-suited to be used as spin filters due to spin dependent tunneling barrier. Here, the homogeneity of the films is essential to form tunneling barriers. Furthermore, the cation ordering on the different sublattices of the inverse spinel structure determines the magnetic properties of the ferrite films which is crucial for the performance as a spin filter. Therefore, the formation of ferrite films has to be carefully controlled if high quality devices are aimed for.

Hence, in this work ultrathin ferrite films of different thicknesses are prepared via reactive molecular beam epitaxy (RMBE) on SrTiO₃(001). In order to investigate structural strain and ordering effects in the films, synchrotron radiation grazing incidence x-ray diffraction (SR-GIXRD) experiments are performed. The chemical composition and structural ordering at the surface are investigated by x-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED), respectively. Magnetic properties are characterized via superconducting quantum interference device (SQUID) magnetometry.