Journal Article

FZJ-2020-04504

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Tuning the Co/Sr stoichiometry of SrCoO$_{2.5}$ thin films by RHEED assisted MBEgrowth

Schöffmann, P. (Corresponding author)FZJ* ; Pütter, S.FZJ* ; Schubert, J.FZJ* ; Zander, W. ; Barthel, J.FZJ* ; Zakalek, P.FZJ* ; Waschk, M. ; Heller, R. ; Brückel, T.FZJ*

2020
IOP Publ. Bristol

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Please use a persistent id in citations: http://hdl.handle.net/2128/26199  doi:10.1088/2053-1591/abc58b

Abstract: Strontium cobaltite (SrCoO2.5+δ, SCO) is a fascinating material because of its topotactic structural phase transition caused by a change in oxygen stoichiometry. In the brownmillerite phase (δ = 0) it is an insulating antiferromagnet whereas in the perovskite phase (δ = 0.5) it is a conducting ferromagnet. In contrast, the impact of the varying Co/Sr stoichiometry on the structure has not yet been studied in SCO thin films. Using molecular beam epitaxy we have fabricated SCO thin films of varying Co/Sr stoichiometry. Films with Co excess exhibit a brownmillerite crystal structure with CoO precipitates within the thin film and on the surface. Co deficient films are amorphous. Only for 1:1 stoichiometry a pure brownmillerite structure is present. We find a clear dependence of the Reflection High Energy Electron Diffraction (RHEED) pattern of these thin films on the stoichiometry. Interestingly, RHEED is very sensitive to a Co excess of less than 12% while x-ray diffraction fails to reveal that difference. Hence, using RHEED, the stoichiometry of SCO can be evaluated and tuned in-situ to a high degree of precision, which allows for a quick adjustment of the growth parameters during a sample series.

Keyword(s): Chemical Reactions and Advanced Materials (1st) ; Chemistry (2nd) ; Condensed Matter Physics (2nd)

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Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. Streumethoden (PGI-4)
3. JARA-FIT (JARA-FIT)
4. Halbleiter-Nanoelektronik (PGI-9)
5. Materialwissenschaft u. Werkstofftechnik (ER-C-2)
6. JCNS-FRM-II (JCNS-FRM-II)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)
2. 524 - Controlling Collective States (POF3-524) (POF3-524)
3. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
4. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)
5. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2020

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