Investigation of a charge transfer at complex oxide interfaces

Abstract

Inspired by the theoretical work suggesting a simple method to predict the charge transfer between any chosen transition metal oxide (TMO) at their interface, this study provided experimental evidence on the charge transfer between TMO pairs of SrVO3/SrNbO3 and LaTiO3/LaMnO3. XPS core level spectra of the transition metal sites are utilized to monitor the valence changes of the transition metal sites. Valence state information gathered from the bulk and the interface sites, are compared to draw conclusions on the charge transfer at the interfaces. Due to compounds SrVO3 and SrNbO3 containing highly degenerate energy levels, XPS spectrum interpretation became challenging. By using final-state effects to explain the multi-peak structure appearance in XPS core level spectra of Nb and V, meaningful results on the charge transfer are gathered. Nb ion sites demonstrated a shift from Nb+4 towards Nb+5 at the interface states, suggesting charge transfer from SrNbO3 layer to SrVO3 layer. For LaTiO3/LaMnO3 pair, even though observation of a slight shift in the Mn+3 valence state towards the Mn+2 was made, it could not be quantified due to the characteristic of the peak fitting method.

Date of Award	15 Aug 2017
Original language	English
Awarding Institution	University of Twente
Supervisor	A.J.H.M. Rijnders (Supervisor 1), G. Koster (External coach), P.J. Kelly (External coach) & J. Geessinck (External coach)