Two-dimensional t-J model at moderate doping
Institute of Physics, University of Tartu, Riia 142, 51014
2 Institut für Physik, Technische Universität, 09107 Chemnitz, Federal Republic of Germany and School of Engineering and Science, International University Bremen, Campus Ring 1, 28759 Bremen, Federal Republic of Germany
Published online: 1 April 2003
Using the method which retains the rotation symmetry of spin components in the paramagnetic state and has no preset magnetic ordering, spectral and magnetic properties of the two-dimensional t-J model in the normal state are investigated for the ranges of hole concentrations and temperatures . The used hopping t and exchange J parameters of the model correspond to hole-doped cuprates. The obtained solutions are homogeneous which indicates that stripes and other types of phase separation are not connected with the strong electron correlations described by the model. A series of nearly equidistant maxima in the hole spectral function calculated for low T and x is connected with hole vibrations in the region of the perturbed short-range antiferromagnetic order. The hole spectrum has a pseudogap in the vicinity of and . For the shape of the hole Fermi surface is transformed from four small ellipses around to two large rhombuses centered at (0,0) and . The calculated temperature and concentration dependencies of the spin correlation length and the magnetic susceptibility are close to those observed in cuprate perovskites. These results offer explanations for the observed scaling of the static uniform susceptibility and for the changes in the spin-lattice relaxation and spin-echo decay rates in terms of the temperature and doping variations in the spin excitation spectrum of the model.
PACS: 71.10.Fd – Lattice fermion models / 74.25.Ha – Magnetic properties / 74.25.Jb – Electronic structure
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003