Microwave spectroscopy of unconventional metals, superconductors and insulators

社会目前正在从半导体电子革命中获益，这场革命发生在20世纪初人们了解了非相互作用电子的量子行为之后。世界各地的许多研究人员都希望，当我们理解一个困难得多的量子问题--强相互作用电子系统的行为时，电子材料将发生第二次革命。在这个阶段，挑战是根本的：了解重要的电子性质是如何在相互作用的电子系统中出现的，并利用这些材料，使它们以受控的方式产生所需的性质。其中许多材料表现出不同寻常的超导电性，这种物质的状态是所有的电阻都消失了。例如铜酸盐高温超导体；所谓的重费米子材料，其中的电子似乎比正常情况下重100到1000倍；以及最近发现的铁基超导体。目前，这些材料中的任何一种都不能很好地理解超导的机制。此外，非超导态是不寻常的金属，对我们理解固体中的电子构成了一些最大的挑战。

Society is currently reaping the benefits of the revolution in semiconductor electronics that occurred after the quantum behaviour of noninteracting electrons was understood in the early 20th century. It is the hope of many researchers around the world that there will be a second revolution in electronic materials when we understand a far more difficult quantum problem - the behaviour of systems of strongly interacting electrons. At this stage the challenges are fundamental: to understand how the important electronic properties emerge in systems of interacting electrons, and to harness these materials so that they produce the desired properties in a controlled way. Many of these materials display unusual forms of superconductivity, a state of matter in which all electrical resistance vanishes. Examples include the cuprate high temperature superconductors; the so-called "heavy fermion" materials, in which electrons appear to be 100 to 1000 times heavier than normal; and the recently discovered iron-based superconductors. At present, the mechanism responsible for superconductivity is not well understood in any of these materials. In addition, the nonsuperconducting states are unusual metals that pose some of the greatest challenges to our understanding of electrons in solids.