Electronic and optical properties of correlated systems using synchrotron radiation

摘要

The newly emerging phenomena of correlated systems such as two-dimensional electron gas (2DEGs), multiferroics and exciton effect require us to elucidate the mechanisms, especially the electronic structure behind them. However, although there have been many techniques based on the study of electronic structure, few experimental techniques are able to probe electronic structure especially distinguish the localized and delocalized charges without disturbing the overlayer and parent materials. Synchrotron radiation, offering intense and collimated photon beams with high peak brightness, short pulse time and easy wavelength tenability, is one of the best choices to directly and comprehensively probe spectral weight transfers (SWT) and interfacial electronic structures. In this thesis, I will describe how to use combined techniques based on synchrotron radiation to study the electronic structures in correlated perovskite systems. Three kinds of perovskite systems are selected here for studying, which are (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) and Sr0.5(Al0.5Ta0.5)O3/SrTiO3 (SATO/STO) films with 2DEGs at the interfaces, EuTiO3 (ETO) and (Eu0.5Ba0.5)TiO3 (EBTO) with multiferroics and metal insulator transition properties, and organic perovskite CH3NH3PbBr3 with strong exciton effect.