Coherent X-ray scattering of charge order dynamics and phase separation in titanates

Oxides of transition metals display a plethora of fundamentally interesting and potentially technologically relevant properties, including metallic, semiconducting, insulating, magnetic and superconducting behavior. The foundations for this flexibility lie in the close balance between the factors controlling the charge, orbital and spin degrees of freedom in such oxides. One characteristic of many complex oxides are phase transitions between different quantum states of matter, for example between a conducting and insulating state or between a paramagnetic and magnetically ordered state. In this thesis, we describe the experiments on the metal-insulator transition (MIT) in a family of doped titanium oxides, Er_0.6Ca _0.4TiO₃.
Rather than simply switching between metallic and insulating states, these systems display coexistence of these antagonistic phases, and the investigation of their interplay and dynamics lies at the heart of this thesis project. Advanced X-ray techniques, using both hard and soft X-rays - from storage ring and free electron laser sources - have been adopted and adapted to probe the phase separation occurring near the MIT in the Er_0.6Ca_0.4TiO₃ system.