%0 Journal Article
%A Schöffmann, P.
%A Pütter, S.
%A Schubert, Jürgen
%A Zander, W.
%A Barthel, J.
%A Zakalek, P.
%A Waschk, M.
%A Heller, R.
%A Brückel, T.
%T Tuning the Co/Sr stoichiometry of SrCoO$_{2.5}$ thin films by RHEED assisted MBEgrowth
%J Materials Research Express
%V 7
%@ 2053-1591
%C Bristol
%I IOP Publ.
%M FZJ-2020-04504
%P 116404
%D 2020
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000587061000001
%R 10.1088/2053-1591/abc58b
%U https://juser.fz-juelich.de/record/887898