| speaker: | L. N. Oliveira, Instituto de Fisica de Sao Carlos, University of Sao Paulo, Sao Carlos, Brazil |
| time: | Th. 10.04.03, 9:00 - 9:50 |
A review of renormalization-group approaches to the computation of physical properties for the two-impurity Kondo model will be presented. Early work and more recent successes will be discussed, with emphasis on the calculation of the impurity magnetic susceptibility and on results for the spectral density. Results for (i) the magnetic susceptibility and (ii) the low energy spectrum as a function of the distance R separating the impurities will be presented. It will be shown that the R-dependence of the low energy spectrum allows one to determine the size of Kondo screening cloud. Results showing that the cloud radius R_{screen} is substantially smaller than the simplistic estimate R_{screen} = v_F/k_BT_K, where v_F is the Fermi velocity and T_K the Kondo temperature, will be presented compared with estimates based on alternative, approximate approaches.