Regensburg 2013 – scientific programme
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DS: Fachverband Dünne Schichten
DS 30: Thin Film Characterization: Structure Analysis and Composition (XRD, TEM, XPS, SIMS, RBS,...) II
DS 30.7: Talk
Thursday, March 14, 2013, 16:15–16:30, H32
Momentum-resolved Energy Loss Spectroscopy of Ultrathin Oxide Layers — •Kinyanjui Michael1, Gerd Benner2, Giuseppe Pavia2, Nicolas Gauquelin3, Gianluigi Botton3, Hans-Ulrich Habermeier4, Eva Benckiser4, Bernhard Keimer4, and Ute Kaiser1 — 1University of Ulm, Central Facility of Electron Microscopy, Albert-Einstein Allee 11, 89081, Ulm, Germany — 2Carl Zeiss NTS GmbH, Oberkochen, Germany — 3Canadian Centre For Electron Microscopy, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada — 4Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70579 Stuttgart, Germany, N. N.
Momentum-resolved electron-energy loss spectroscopy (MREELS) is a technique suitable for the study of momentum dependence (dispersion) of electronic excitations as well as excitations in anisotropic systems, including hidden interfaces which are hard to study with x-ray scattering. Here we report on the acquisition of MREELS spectra from ultra-thin LaNiO3-LaAlO3 layers grown on LaSrAlO4 substrate using nano-beam electron diffraction (NBED). With NBED we obtained a nearly parallel electron beam with a spot size ~ 1.5 nm which is slightly smaller than the layer thickness of one LaNiO3 /LaAlO3 layer (layer thickness ~ 1.7 nm). We observe features in the EELS spectra which are identified as collective electron excitations arising at the interface. This observation is supported by associated EELS spectra calculations for super-lattices. From MREELS we were also able to resolve the dispersion of the observed interfacial collective excitations.