New Physics of Metals: Fermi Surfaces Without Fermi Liquids

For some 40 years almost all electronic phenomena in metals have been interpreted in terms of a general theoretical framework which one could variously call renormalized free particle theory, Fermi liquid theory, or “AGD” after the best-known book on the subject. I came to the conclusion a few years ago that this theory is, in very many of the most interesting cases, basically a failure. For the first 20 years of its history, until the mid-70s, it served us very well; but then as we began to focus on the most interesting (or the most anomalous) cases, more and more of the copious literature of our subject came to be engaged in fitting the proverbial square peg into a round hole. It is not that there are no instances which fit the framework, but that, contrary to the claims for universality which are been made for it, it seems that for systems with strong interactions, it often is completely misguided.