Veranstaltungsdetails

20.4.2006, 15:30
Jungiusstr. 11, Hörsaal AP

SFB 668 - Kolloquium

Dr. Ivica Zerec (Max-Planck-Institut für Chemische Physik fester Stoffe):

Kondo lattice model on finite 2D clusters with finite temperature Lanczos method

The competition between the Kondo screening and the RKKY interaction for the Kondo lattice model at half filling is considered on finite 2D clusters using the finite temperature Lanczos method. The thermodynamic and spin correlation functions are calculated, as well as the total local magnetic moment. The results are used to construct the phase diagram of the 2D cluster. It is found that by varying boundary conditions, two different regimes in the weak coupling limit are found, depending on the distribution of unperturbed conduction electron levels. If there are levels at the Fermi energy, the moments are first partially screened and then the unscreened parts ´order´ antiferromagnetically at lower temperature due to the RKKY interaction; there are two characteristic temperatures. Otherwise the screening and the ´ordering´ take place at the same temperature, determined by the RKKY interaction.