Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.53: Poster
Wednesday, March 13, 2013, 15:00–19:00, Poster D
Localized and delocalized interface states in LaAlO3/SrTiO3 heterostructures as probed by resonant inelastic x-ray scattering — •Florian Pfaff1, Hidenori Fujiwara2, Yoshito Nishitani3, Yoshihisa Harada4, Shigemasa Suga2, Michael Sing1, and Ralph Claessen1 — 1Physikalisches Institut, Universität Würzburg — 2Graduate School of Engineering Science, Osaka University — 3Department of Physics, Konan University — 4Institute for Solid State Physics, University of Tokyo
The interface between the two band insulators LaAlO3 (LAO) and SrTiO3 (STO) hosts a two-dimensional electron system of itinerant charge carriers above a critical LAO overlayer thickness of 3 monolayers. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Recently, two peaks in resonant inelastic x-ray scattering (RIXS) indeed have been correlated with delocalized and localized charge carriers [1]. To shed light on the coexistence of the two types of Ti 3d carriers we performed RIXS on LAO/STO heterostructures with different overlayer thicknesses and different concentrations of oxygen vacancies. While there is an increase of the total charge seen in RIXS with increasing film thickness for samples showing the critical thickness behavior, surprisingly, the spectrum remains unchanged for samples that have been intentionally doped with oxygen vacancies. We discuss this in terms of the electronic reconstruction scenario and a possible non equilibrium situation due to the generation of electron-hole pairs during irradiation.
[1] Ke-Jin Zhou et al., Phys. Rev. B 83, 201402(R) (2011)