Phononic and Electronic Excitations in Complex Oxides Studied with Advanced Infrared and Raman Spectroscopy Techniques

This PhD thesis reports on investigations of several oxide-based materials using advanced infrared and Raman spectroscopy techniques and in combination with external stimuli such as high magnetic or electric field, sptial confinement in thin film heterostructures and the radiation with UV light. This leads to new results in the fields of superconductivity, electronic polarization states and nanoscale phenomena.

Among these, the observation of anomalous polar moments is of great relevance for understanding the electric-field-induced metal-to-insulator transistion; and the demonstration that confocal Raman spectroscopy of backfolded acoustic photons in metal-oxide multilayers  can be used as a powerful characterization tool for monitoring their interface properties and layer thickness is an important technical development for the engineering of such functional oxide heterostructures. 

Introduction.- Scientific Background of Complex Oxides.- Experimental Techniques.- Magnetic Field Effect on the Infrared Response of Underdoped YBa2Cu3O6.-Observation of Backfolded Acoustic Phonons in Metal-Oxide Heterostructures.

Fryderyk Lyzwa was born in 1990 in Göttingen, Germany. He went to High school in Germany, France and the USA. His Bachelor and Master in physics he performed at the Universitá di Bologna, Italy and at the Georg-August University of Göttingen under the supervision of Prof. Dr. Vasily Moshnyaga, where he finished with distinction. For his PhD he joined the group of Prof. Dr. Christian Bernhard at the Université de Fribourg, Switzerland. 

During this time, Fryderyk Lyzwa conducted research at the Physics Department in Fribourg, the High-Magnetic field Laboratory (LNCMI) in Grenoble, France and the Max Planck Institute for Solid State Research in Stuttgart, Germany on complex oxide systems with optical spectroscopy techniques. Afterwards, he was a visiting scientist at the Max Planck Institute for Solid State Research in the Department of Prof. Dr. Bernhard Keimer. Since then, he has continued to research as a postdoctoral scientist at the National Synchrotron Light Source II, Brookhaven National Laboratories in New York, USA.