TY  - JOUR
AU  - Schöffmann, P.
AU  - Pütter, S.
AU  - Schubert, Jürgen
AU  - Zander, W.
AU  - Barthel, J.
AU  - Zakalek, P.
AU  - Waschk, M.
AU  - Heller, R.
AU  - Brückel, T.
TI  - Tuning the Co/Sr stoichiometry of SrCoO$_{2.5}$ thin films by RHEED assisted MBEgrowth
JO  - Materials Research Express
VL  - 7
SN  - 2053-1591
CY  - Bristol
PB  - IOP Publ.
M1  - FZJ-2020-04504
SP  - 116404
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000587061000001
DO  - DOI:10.1088/2053-1591/abc58b
UR  - https://juser.fz-juelich.de/record/887898
ER  -