Spectral scaling and quantum critical behaviour in the pseudogap Anderson model

Oxford University, Physical and Theoretical Chemistry Laboratory South Parks Road, Oxford OX1 3QZ, UK

Received: 4 November 2002
Accepted: 14 January 2003

Abstract

The pseudogap Anderson impurity model provides a classic example of an essentially local quantum phase transition. Here we study its single-particle dynamics in the vicinity of the symmetric quantum critical point (QCP) separating generalized Fermi-liquid and local-moment phases, via the local-moment approach. Both phases are shown to be characterized by a low-energy scale that vanishes at the QCP; and the universal scaling spectra, on all energy scales, are obtained analytically. The spectrum precisely at the QCP is also obtained; its form showing clearly the non–Fermi-liquid, interacting nature of the fixed point.