Metals, Insulators, and Superconductors

理论将发展为金属，绝缘体和超导体的电子和振动特性，特别是晶体氧化物，如铜和铋氧化物超导体和钒氧化物金属绝缘体系统。潜在的动机是探索仍然不清楚的高温超导机制。这项研究的第二个动机是提高对这些材料的多种和鲜为人知的电输运性质的理解。作为一种模型体系，我们将对钡铋氧化物进行详细的研究。这个绝缘体中的载流子是双极化子。当铋被铅取代时，从奇异的超导状态到正常的金属导体的连续演变就发生了。极化子和双极化子模型将开发和测试，以模拟电阻率，霍尔系数和超导性。其他要研究的模型系统是氧化铌和二氧化钒。后者在温度下具有金属绝缘体过渡，便于器件应用，如存储元件。研究了晶格畸变和声子对跃迁的影响。热传导也将在非晶硅模型中进行研究。

Theory will be developed for the electronic and vibrational properties of metals, insulators and superconductors, especially crystalline oxides such as copper-and bismuth-oxide superconductors and vanadium-oxide based metal-insulator systems. The underlying motive is to explore the still obscure mechanism for high temperature superconductivity. A secondary motive for the research is to improve understanding of the diverse and poorly understood electrical transport properties of these materials. As a model system barium-bismuth-oxide will be studied in detail. The charge carriers in this insulator are bipolarons. A continuous evolution through an exotic superconducting state to a normal metallic conductor occurs as bismuth is replaced by lead. Polaron and bipolaron models will be developed and tested to model resistivity, Hall coefficient, and superconductivity. Other model systems to be studied are niobium-oxide and vanadium-dioxide. The latter has a metal-insulator transition at a temperature convenient for device applications such as memory elements. The effect of lattice distortion and phonons on the transition will be studied. Thermal conduction will also be studied in a model of amorphous silicon.