Temperature (field) dependent phase shifts: A useful tool in the approach to the Kondo problem

Abstract

A number of illusrtations are given which experimentally support the affirmation contained in the title and underline the ability of the model to provide easy predictions for a variety of effects (resistance, magnetoresistance, susceptibility, magnetization, specific heat). The approximation involved is equivalent to one which has been, to some extent, justified in sophisticated extensions of the sd model and amounts to the definition of an effective temperature dependent exchange integral; thus Abrikosov’s approximate solution, 2 Jeff(T/TK) ρ∠2 Jρ/[1−2 Jρ ln(kT/D)] implies, in our model, a temperature dependence of the phase shift which leads to the Hamann Fischer solution for the resistivity. Other properties are also discussed (susceptibility, re‐entrant Tc(c) curves, etc...) with emphasis put on the interesting physical picture which the model in addition provides.