Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 37: Metal Oxide Surfaces II: Structure, Epitaxy and Growth

O 37.3: Vortrag

Dienstag, 2. April 2019, 14:30–14:45, H16

High quality MgO-films grown at low temperatures on CoO(100) — •Alexandra Schewski, Tilman Kisslinger, Lutz Hammer, and Alexander Schneider — Lehrstuhl für Festkörperphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg

Interfaces between oxides have recently received great attention showing that new electronic properties [1] but also an influence on magnetic transition temperatures can be observed, e.g. for rocksalt CoO on Fe₃O₄[2]. In all these cases it is important to prepare a high quality interface and ideally characterize its structure.

Here we report on the growth and characterization of the non-magnetic insulator MgO on the anti-ferromagnet CoO. As a substrate we used CoO(100) films on Ir(100) that grow perfectly with terrace sizes larger than 200 nm [3]. On top, we deposited Mg reactively in an oxygen atmosphere at different temperatures and subsequently annealed up to a maximum of 1270 K. Surprisingly, even low-temperature deposition at 90 K leads to well-ordered, closed films with a sharp (1×1) LEED-pattern. The LEED-I(V) analysis confirms pure MgO(100) overlayers. It is remarkable that the film quality does hardly improve by annealing up to 870 K. Annealing beyond this temperature leads to the recovery of the CoO(100) LEED-pattern due to a dewetting of the MgO on the surface. The formed micrometer sized MgO particles on CoO are readily identified by SEM.

[1] F. Hellmann et al. Rev. Mod. Phys., 89, 025006 (2017).

[2] Y. Ijiri et al. , Phys. Rev. Lett. 99, 147201 (2007).

[3] K. Heinz, L. Hammer, J. Phys.-Condens. Mat. 25 173001 (2013)