9.7.2009, 15:15-16:15 SR 4.


Interfaces of Correlated Electron Systems

Thilo Kopp

Univ. Augsburg

Interfaces in complex transition metal oxide heterostructures can play an important role for their physical properties. This is especially important for heterostructures which contain nm-thick films deposited on structurally compatible substrate layers. The lattice mismatch and the charge polarity due to structural discontinuities at a film-substrate interface are the driving forces of interfacial reconstruction which changes dramatically the interface electronic state and possibly the physical behavior of the entire film.
Frequently used as a model system for oxide interfaces, the interface between the charge transfer insulators LaAlO3 and TiO3-terminated SrTiO3 forms an especially peculiar ultra-thin metallic state with fascinating properties. At low temperatures, for example, this state forms a tunable, two-dimensional superconductor. However, little is known about the microscopic nature of this electronic phase. We have therefore investigated the electronic structure of the interfaces by scanning tunneling spectroscopy (STS). The density of states (DOS) determined by STS is in excellent agreement with local density approximation calculations, if sufficiently strong on-site repulsion is taken into account.