Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.26: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Surface studies of charge-ordering transition metal oxides by means of scanning tunneling microscopy — Paul Sass1, •Dirk Bombor1, Grzegorz Urbanik1, Torben Hänke1, Christian Hess1, Bernd Büchner1, Pascal Reutler2, and Alexandre Revcolevschi2 — 1Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Germany — 2Laboratoire de Physico-Chimie de l’Etat Solide, Université Paris Sud, France
The surface of the transition metal oxides La5/3Sr1/3NiO4 and La0.5Sr1.5MnO4 was studied by means of scanning tunneling microscopy (STM). Both materials are model systems for charge ordering phenomena. Despite the insulating nature of these materials we achieved atomic resolution on cleaved surfaces of La5/3Sr1/3NiO4 and La0.5Sr1.5MnO4. Topogrophic images of both compounds reveal periodic modulations, which can be interpreted as signature of short range surface charge ordering. Nevertheless, no direct evidence of charge ordering structures which appear in the volume was found on the surface of our samples. Spectroscopic investigations of the manganite La0,5Sr1,5MnO4 reveal changes in density of states at the fermi level with decreasing temperature, especially an enhacement of the energy gap at the charge ordering temperature.