Quantum Criticality in Heavy Fermion Metals

TL;DR

This paper reviews the role of quantum criticality in heavy fermion metals, exploring how these systems serve as models for understanding complex phenomena like non-Fermi liquid behavior and unconventional superconductivity at quantum phase transitions.

Contribution

It provides a comprehensive overview of experimental and theoretical insights into quantum criticality in heavy fermion systems, highlighting challenges to standard theories and the interplay with superconductivity.

Findings

Quantum criticality extends beyond standard order-parameter fluctuation theories.

The Kondo effect exhibits unique behavior in the quantum critical regime.

Non-Fermi liquid phenomena are closely linked to quantum critical points.

Abstract

Quantum criticality describes the collective fluctuations of matter undergoing a second-order phase transition at zero temperature. Heavy fermion metals have in recent years emerged as prototypical systems to study quantum critical points. There have been considerable efforts, both experimental and theoretical, which use these magnetic systems to address problems that are central to the broad understanding of strongly correlated quantum matter. Here, we summarize some of the basic issues, including i) the extent to which the quantum criticality in heavy fermion metals goes beyond the standard theory of order-parameter fluctuations, ii) the nature of the Kondo effect in the quantum critical regime, iii) the non-Fermi liquid phenomena that accompany quantum criticality, and iv) the interplay between quantum criticality and unconventional superconductivity.