Department of Physics Colloquium, Harold Hwang, Stanford University. Refreshments at 3:30pm.
Abstract: Complex oxides are fascinating systems which host a vast array of unique phenomena, such as high temperature (and unconventional) superconductivity, ‘colossal’ magnetoresistance, all forms of magnetism and ferroelectricity, as well as (quantum) phase transitions and couplings between these states. In recent years, there has been a mini-revolution in our ability to grow thin film heterostructures of these materials with atomic precision. With this level of control, a number of new electronic phases have been discovered at their interfaces. Between two insulators, for example, metallic, superconducting, and magnetic states can be induced. In analogy to the rich science and technology that emerged from the development of semiconductor heterostructures, we are using these techniques to create novel low-dimensional states inaccessible in bulk oxides. After a general overview, I will focus on recent results on two-dimensional superconductivity in oxide heterostructures, contrasting two systems based on SrTiO3 which approach the ‘dirty’ and ‘clean’ limit.