Spectral functions in itinerant electron systems with geometrical frustration

The Hubbard model with geometrical frustration is investigated in a metallic phase close to half-filling. We calculate the single particle spectral function for the triangular lattice within dynamical cluster approximation, which is further combined with noncrossing approximation and fluctuation exchange approximation to treat the resulting cluster Anderson model. It is shown that frustration due to nonlocal correlations suppresses short-range antiferromagnetic fluctuations and thereby assists the formation of heavy quasiparticles near half-filling.