Title:	Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content
Authors:	Thien, Jannis Rodewald, Jari Pohlmann, Tobias Ruwisch, Kevin Bertram, Florian Küpper, Karsten Wollschläger, Joachim
ORCID of the author:	https://orcid.org/0000-0001-5551-7240 https://orcid.org/0000-0002-3043-3718 https://orcid.org/0000-0003-0364-9385 https://orcid.org/0000-0001-9304-3015
Abstract:	Ultrathin Co𝑥Fe3−𝑥O4 films of high structural quality and with different Co content (x = 0.6–1.2) were prepared by reactive molecular beam epitaxy on MgO(001) substrates. Epitaxy of these ferrite films is extensively monitored by means of time-resolved (operando) X-ray diffraction recorded in out-of-plane geometry to characterize the temporal evolution of the film structure. The Co ferrite films show high crystalline ordering and smooth film interfaces independent of their Co content. All Co𝑥Fe3−𝑥O4 films exhibit enhanced compressive out-of-plane strain during the early stages of growth, which partly releases with increasing film thickness. When the Co content of the ferrite films increases, the vertical-layer distances increase, accompanied by slightly increasing film roughnesses. The latter result is supported by surface-sensitive low-energy electron diffraction as well as X-ray reflectivity measurements on the final films. In contrast, the substrate–film interface roughness decreases with increasing Co content, which is confirmed with X-ray reflectivity measurements. In addition, the composition and electronic structure of the ferrite films is characterized by means of hard X-ray photoelectron spectroscopy performed after film growth. The experiments reveal the expected increasing Fe3+/Fe2+ cation ratios for a higher Co content.
Citations:	Thien J, Rodewald J, Pohlmann T, Ruwisch K, Bertram F, Küpper K, Wollschläger J.: Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content. Materials. 2023; 16(23):7287
URL:	https://doi.org/10.48693/516 https://osnadocs.ub.uni-osnabrueck.de/handle/ds-2024022810912
Subject Keywords:	cobalt ferrite; ultrathin films; strain; X-ray diffraction
Issue Date:	23-Nov-2023
License name:	Attribution 4.0 International
License url:	http://creativecommons.org/licenses/by/4.0/
Type of publication:	Einzelbeitrag in einer wissenschaftlichen Zeitschrift [Article]
Appears in Collections:	FB06 - Hochschulschriften Open-Access-Publikationsfonds

This item is licensed under a Creative Commons License