Pseudogaps in the t-J model:: An extended dynamical mean-field theory study -: art. no. 155119

We investigate the highly incoherent regime of hole-doped two-dimensional Mott-Hubbard insulators at moderately small doping delta and temperatures greater than or similar to0.1J, where J is the exchange coupling. Within an extended dynamical mean-field theory of the t-J model and a generalized noncrossing approximation we calculate the single-particle spectral function, the dynamical susceptibility, and thermodynamic and transport quantities. Short-ranged antiferromagnetic fluctuations lead to strongly incoherent single-particle dynamics, large entropy, and large electrical resistivity. At low doping a pseudogap is found to open up in both the single-particle and spin excitation spectra, leading to a decrease in entropy and resistivity. The Hall coefficient changes sign to positive values upon lowering the doping level and increases inversely proportional to delta.