Critical Kondo destruction and the violation of the quantum-to-classical mapping of quantum criticality

TL;DR

This paper investigates the failure of traditional order-parameter theories in describing the Kondo destruction quantum critical point in heavy fermion systems, highlighting deviations from the quantum-to-classical mapping.

Contribution

It analyzes the breakdown of the standard order-parameter functional at the Kondo-destroying quantum critical point within the Bose-Fermi Kondo model.

Findings

Standard order-parameter functional fails at the critical point

Quantum-to-classical mapping is violated in this context

Highlights the need for alternative theoretical approaches

Abstract

Antiferromagnetic heavy fermion metals close to their quantum critical points display a richness in their physical properties unanticipated by the traditional approach to quantum criticality, which describes the critical properties solely in terms of fluctuations of the order parameter. This has led to the question as to how the Kondo effect gets destroyed as the system undergoes a phase change. In one approach to the problem, Kondo lattice systems are studied through a self-consistent Bose-Fermi Kondo model within the Extended Dynamical Mean Field Theory. The quantum phase transition of the Kondo lattice is thus mapped onto that of a sub-Ohmic Bose-Fermi Kondo model. In the present article we address some aspects of the failure of the standard order-parameter functional for the the Kondo-destroying quantum critical point of the Bose-Fermi Kondo model.