A new renormalization group approach for systems with strong electron correlation

Abstract

The anomalous low energy behaviour observed in metals with strong electron correlation, suchas in the heavy fermion materials, is believed to arise from the scattering of the itinerantelectrons with low energy spin fluctuations. In systems with magnetic impurities this scatteringleads to the Kondo effect and a low energy renormalized energy scale, the Kondo temperatureTK. It has been generally assumed that these low energy scales can only be accessed by anon-perturbative approach due to the strength of the local inter-electron interactions. Herewe show that it is possible to circumvent this difficulty by first suppressing the spinfluctuations with a large magnetic field. As a first step field-dependent renormalizedparameters are calculated using standard perturbation theory. A renormalizedperturbation theory is then used to calculate the renormalized parameters for areduced magnetic field strength. The process can be repeated and the flow of therenormalized parameters continued to zero magnetic field. We illustrate the viabilityof this approach for the single impurity Anderson model. The results for therenormalized parameters, which flow as a function of magnetic field, can be checkedwith those from numerical renormalization group and Bethe ansatz calculations.