FRIEDEL OSCILLATIONS INDUCED BY NONMAGNETIC IMPURITIES IN THE 2-DIMENSIONAL HUBBARD-MODEL

We study the interplay of correlations and disorder using an unrestric ted slave-Boson technique in real space. Within the saddle-point appro ximation, we find Friedel oscillations of the charge density in the vi cinity of a single nonmagnetic impurity, in agreement with numerical s imulations. The corresponding amplitudes are suppressed by repulsive i nteractions, while attractive correlations lead to a charge-density-wa ve enhancement. In addition, we investigate the spatial dependence of the local magnetic moment and the formation of a magnetic state at the impurity site.