Quantum Phase Transitions and Correlated Electrons

TL;DR

This paper introduces the physics of quantum phase transitions in metallic systems, emphasizing the role of non-Fermi liquid behavior and local quantum critical points in heavy fermion metals and other correlated electron systems.

Contribution

It highlights the connection between non-Fermi liquid behavior and new classes of quantum phase transitions, with a focus on local quantum criticality in heavy fermion metals.

Findings

Evidence for local quantum critical points in heavy fermion metals

Non-Fermi liquid behavior can induce quantum phase transitions

Relevance to doped Mott insulators and other correlated systems

Abstract

This article is aimed at a pedagogical introduction to the physics of quantum phase transitions that is unique to metallic systems. It has been recognized for some time that quantum criticality can result in a breakdown of Landau's Fermi liquid theory. Its converse, however, has not been appreciated until very recently: non-Fermi liquid behavior can in turn lead to new classes of quantum phase transition. A concrete example is provided by ``local quantum critical points''. I summarize the theoretical reasoning and experimental evidence for local quantum criticality, in the context of heavy fermion metals. The underlying physics is likely to be relevant to other correlated electron systems including doped Mott insulators.