Ordering Phenomena in Transition Metal Oxides

Scanning tunneling microscopy and spectroscopy at surfaces of transition metal oxides   

Conceptually, creating a surface by cleaving a single crystal is a controlled way to disturb the coupled system by breaking the symmetry without changing the stoichiometry. It provides the opportunity to study the coupling mechanism between structural, electronic, and magnetic properties. Cleaved surfaces of the p-wave superconductor Sr₂RuO₄ show a reconstruction characterized by rotation of the RuO₆ octahetra. This kind of reconstruction is common in the bulk of sister-compounds where it is closely coupled to the magnetic properties. In the second part of the talk we will present low-temperature scanning tunnelling spectroscopy data from the quasi one-dimensional purple bronze Li_0.9Mo₆O₁₇. The density of states near Fermi-energy of this material is discussed in terms of Luttinger-liquid behaviour and zero-bias anomaly.