  We report an angular resolved photoemission study of Na0.73CoO2 where it is
found that the renormalization of the quasiparticle (QP) dispersion changes
dramatically upon a rotation from GM to GK. The comparison of the experimental
data to the calculated band structure reveals that the QP-renormalization is
most pronounced along the GK-direction, while it is significantly weaker along
the GM-direction. We discuss the observed anisotropy in terms of multiorbital
effects and point out the relevance of magnetic correlations for the band
structure of Na0.73CoO2.
