https://doi.org/10.1140/epjb/e2003-00090-x
Two-dimensional t-J model at moderate doping
1
Institute of Physics, University of Tartu, Riia 142, 51014
Tartu, Estonia
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
Received:
14
November
2002
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
