Theory of complex oxides: superconductivity and interfaces

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Modern technology---computers, cell phones, medical equipment---is possible because of a decades-long push towards making smaller and faster electronic devices. This exponential growth of computing power over time is known as Moore's law. As we begin to bump up against fundamental limits to Moore's law, interest is growing in broadening the capabilities of nano-electronic devices. For example, the past decade has seen significant amounts of basic research devoted to ferroelectric and magnetic materials that might, one day, be incorporated into new high-speed memory devices. To this end, research is moving away from traditional semiconductors into new families of materials. My work focuses on transition metal oxides.******Transition metal oxides hold a lot of potential because they can have many properties---superconductivity, magnetism, ferroelectricity, and others---that are not found in conventional semiconductors. At present, the questions that need to be answered are very basic: can we understand, in terms of the fundamental laws of nature, how these materials behave? It turns out that many transition metal oxides have different physical properties in confined geometries (for example, nanodevices) than they do in large samples. Can we understand why? In my research, I construct computer models, based on fundamental laws of physics, to simulate the electronic properties of various transition metal oxides. With these models, I hope to explain the physical properties of simple oxide structures (interfaces and heterostructures), and to understand the subtle role played by impurities and defects.******My research focuses on two families of materials: high temperature superconductors and strontium titanate interfaces. The first of these families was discovered almost 30 years ago, but continues to surprise us with new revelations of complex self-organised behaviour that emerges on nanometre scales. The second family has more immediate potential for applications in nanoelectronics, but also raises questions about how electrons behave at the nanometre scale; here the fundamental goal is to explore the vast range of possible properties that can be engineered into devices by appropriate choice of building materials and geometry.