Strongly Correlated and Disordered Fermi Systems

[9529138 . kotlie]这项拨款涉及那些在弱相互作用清洁物质中不存在的，但由于强粒子间相互作用和/或缺乏平移不变性而产生的费米系统的性质。这些性质在金属-绝缘体跃迁实验中都有体现。它们对我们理解重费米子、掺杂半导体、非晶合金和高温超导体也至关重要。具体而言，该项目包括三个部分(a)轨道简并系统中的莫特跃迁，(b)局域化与相互作用之间相互作用的大维度分析，以及(c)涡旋晶格熔化过程中量子涨落的影响。一般来说，磁铁是绝缘的（铁钴和镍是非常微妙的例外），超导体在高温下是很好的金属（当它们不是超导的时候）。最近发现的高温超导体表明这些材料属于特殊的一类，超导体的正常状态不是很好的金属，在类似的化合物中有磁性。磁性、脏金属特性和超导性的共存是一个复杂而具有挑战性的理论问题。目前的资助提出了解决这一问题的新方法，并可能理解高温超导现象。* * *

9529138 Kotliar This grant concerns those properties of a Fermi system that are not present in the weakly interacting-clean substances but that arise as a result of the strong interparticle interaction and/or lack of translational invariance. These properties are present in experiments on metal-insulator transitions. They are also critical to our understanding of heavy fermions, doped semiconductors, amorphous alloys and high temperature superconductors. Specifically, the project consists of three parts (a) Mott transition in orbitally degenerate systems, (b) a large dimension analysis of the interplay between localization and interaction and (c) Effect of quantum fluctuations in the melting of a vortex lattice. %%% Typically, magnets are insulating (Iron Cobalt and Nickel are very subtle exceptions) and superconductors are good metals at high temperatures (when they are not superconducting). Recent discoveries of high temperature superconductors show these materials to belong to a special class, where the normal state of a superconductor is not a very good metal and there is magnetism in similar compounds. The puzzling coexistence of magnetism and dirty metallic character and superconductivity is a complex and challenging theoretical problem. The present grant suggests a novel approach to the solution of this problem and possible understanding of the phenomena of high temperature superconductivity. ***