The central focus of this dissertation is the study of crystal systems whose properties are significantly influenced by their transition metal components. Each project follows a systematic approach: we synthesize crystal systems using the molecular beam epitaxy thin film growth technique, characterize these materials through high-resolution spectroscopy measurements---both in-house and using synchrotron radiation---and interpret the underlying physics by comparing our findings with theoretical models.
First, we offer an in-depth study of N substitution in NiO. NiO is regarded as a prototypical strongly correlated material, often serving as a model system for understanding electron-electron interactions. This makes NiO an ideal candidate for our study of individual centers in antiferromagnetic strongly correlated oxides. These centers are imperfections in a crystal lattice that host localized electronic states and magnetic properties, distinct from the surrounding crystal. With the growing interest in quantum technologies, significant efforts have been made to extend individual centers to a wide array of materials. Here, we explore the formation of Ni-N-Ni units upon introducing low concentrations of N into the NiO lattice. These units exhibit properties essential for quantum devices: they are decoupled from the rest of the crystal and possess degenerate quantum states that could be perturbed by external magnetic fields or finite temperatures.
We then study the electronic structures of various Ni-based compounds, namely NiO, N-substituted NiO, and Ca-substituted LaNiO3. We analyze how these structures differ from other systems and their unsubstituted counterparts. In N-substituted NiO, we further investigate its electronic structure through core-level photoemission spectroscopy, examining doping and temperature dependence to deepen our understanding of non-local screening in this material.
Finally, we investigate Ti thin films and their interaction with polar surfaces. Polar materials are characterized by alternating electronically charged layers, leading to surface instabilities that can increase interfacial interactions. We present an experimental technique to stabilize polar MgO (111) and study its impact on the superconducting properties of Ti thin films deposited on this substrate.
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2025-01-30T09:00:002025-01-30T12:00:00Decoupled Magnetic Centers in Anion-substituted Nickel Oxide Event Information:
Abstract:
The central focus of this dissertation is the study of crystal systems whose properties are significantly influenced by their transition metal components. Each project follows a systematic approach: we synthesize crystal systems using the molecular beam epitaxy thin film growth technique, characterize these materials through high-resolution spectroscopy measurements---both in-house and using synchrotron radiation---and interpret the underlying physics by comparing our findings with theoretical models.
First, we offer an in-depth study of N substitution in NiO. NiO is regarded as a prototypical strongly correlated material, often serving as a model system for understanding electron-electron interactions. This makes NiO an ideal candidate for our study of individual centers in antiferromagnetic strongly correlated oxides. These centers are imperfections in a crystal lattice that host localized electronic states and magnetic properties, distinct from the surrounding crystal. With the growing interest in quantum technologies, significant efforts have been made to extend individual centers to a wide array of materials. Here, we explore the formation of Ni-N-Ni units upon introducing low concentrations of N into the NiO lattice. These units exhibit properties essential for quantum devices: they are decoupled from the rest of the crystal and possess degenerate quantum states that could be perturbed by external magnetic fields or finite temperatures.
We then study the electronic structures of various Ni-based compounds, namely NiO, N-substituted NiO, and Ca-substituted LaNiO3. We analyze how these structures differ from other systems and their unsubstituted counterparts. In N-substituted NiO, we further investigate its electronic structure through core-level photoemission spectroscopy, examining doping and temperature dependence to deepen our understanding of non-local screening in this material.
Finally, we investigate Ti thin films and their interaction with polar surfaces. Polar materials are characterized by alternating electronically charged layers, leading to surface instabilities that can increase interfacial interactions. We present an experimental technique to stabilize polar MgO (111) and study its impact on the superconducting properties of Ti thin films deposited on this substrate. Event Location:
Room 288 of the Stewart Blusson Quantum Matter Institute (QMI) building (2355 East Mall)