Negative Impurity Magnetic Susceptibility and Heat Capacity in a Kondo Model with Narrow Peaks in the Local Density of Electron States

摘要

Temperature dependencies of the impurity magnetic susceptibility, entropy,and heat capacity have been obtained by the method of numerical renormalizationgroup and exact diagonalization for the Kondo model with peaks in the electrondensity of states near the Fermi energy (in particular, with logarithmic VanHove singularities). It is shown that these quantities can be {\it negative}. Anew effect has been predicted (which, in principle, can be observedexperimentally), namely, the decrease in the magnetic susceptibility and heatcapacity of a nonmagnetic sample upon the addition of magnetic impurities intoit.