Abstract

Results for the dispersion of “heavy” 4f-derived quasiparticles in Yb-based compounds are presented. The bands are determined by means of the Renormalized Band method. The topology of the Fermi surface differs from the one predicted by standard band structure calculations based on Density Functional Theory. This is in marked contrast to the situation encountered in Ce-based Heavy Fermion Systems where standard band structure calculation usually provide reliable models for the Fermi surface. Calculations of the magnetic-field-induced changes of the heavy quasiparticles in YbRh2Si2 are presented. The progressive de-renormalization of the quasiparticles in the magnetic field is accounted for using field-dependent quasiparticle parameters deduced from Numerical Renormalization Group studies. The results are related to recent measurements of thermodynamic and transport properties.