Magnetic and charge susceptibilities in the half-filled triangular lattice Hubbard model

Abstract

We study the momentum-dependent magnetic and charge susceptibilities in the half-filled two-dimensional triangular Hubbard model within the ladder dual fermion approximation in the metallic, Mott insulating, and crossover regions of parameter space. In the insulating state, we find strong spin fluctuations at the K point at low energy corresponding to the 120^{∘} antiferromagnetic order. The spin spectra of the insulating state is consistent with the inelastic neutron spectra of the triangular compound Ba_{8}CoNb_{6}O_{24}. We also find that the spin fluctuations at the K point persist into the metallic phase and move to higher energy. These results are in agreement with studies of spin-lattice relaxation times in κ-(ET)_{2}Cu_{2}(CN)_{3}. Finally, we present charge susceptibilities in different areas of parameter space, which should correspond to momentum-resolved electron-loss spectroscopy measurements on triangular compounds.