“Emergent Properties in Complex Oxide Heterostructures”
Dr. Anderson Janotti
Materials Department, University of California Santa Barbara
Complex oxides are fascinating materials that host an array of phenomena and physical properties, from which high-Tc superconductivity, colossal magnetoresistance, magnetic ordering ferroelectricity, and high dielectric permittivity are just a few examples. Recent advances in epitaxial growth have led to heterostructures of complex oxides with structural quality that rivals that of conventional semiconductors, revealing interesting properties that are absent in the building block compounds. For example, a two-dimensional electron gas (2DEG) was created at the interface between two normally insulating oxides—SrTiO3/LaAlO3, or between SrTiO3 and a Mott insulator such as GdTiO3. In the case of SrTiO3/GdTiO3, the electron density is an order of magnitude higher than those obtained using conventional semiconductors, sparking the interest in novel device applications. Superconductivity and ferromagnetism have already been reported. In spite of almost a decade of research, the origin of the excess charge at the interface and the mechanisms that determine the density of the 2DEG are still controversial, and fundamental properties of this interfacial metallic state are not fully understood. In this presentation we will discuss how first-principles calculations can provide insights into the origin and nature of the 2DEG. We will report on electron correlation effects and how the electronic structure of these heterostructures can be drastically altered, turning from metallic into insulating, by changing the thickness of the SrTiO3 layer. Finally, we address the potential of oxide heterostructures for future electronic devices, and discuss some design principles.
Anderson Janotti is a Project Scientist in the Materials Department at the University of California, Santa Barbara. After receiving a PhD degree in the area of Semiconductor Physics from the University of Sao Paulo, Brazil, he held postdoctoral positions at the National Renewable Energy Laboratory, CO, and at Oak Ridge National Laboratory, TN, where he worked on novel photovoltaic compound semiconductors, structural materials, and magnetic nanostructures. He joined the University of California, Santa Barbara in 2004. His research interests are in the development and application of electronic structure methods in materials science and materials design. He has contributed to fundamental understanding of physical processes related to defects and doping in oxide and nitride semiconductors for solid state lighting and electronics, transparent conducting oxides, novel photovoltaic materials, hydrogen storage materials, defects as qubits for quantum information, novel channel materials and high-k dielectrics, and complex oxides heterostructures for novel device applications. Dr. Janotti has authored more than 150 publications, and has actively contributed to the scientific community by organizing symposiums and focus topic sessions in major conferences such as the MRS and APS March meeting.
219 Brown Laboratory
Newark, DE 19716
Materials Science & Engineering
University of Delaware
February 5, 2015
9:30 - 10:30 am