Ferroquadrupolar phase of the S=1 bilinear-biquadratic Heisenberg model on the square lattice

Using the SU(3) Schwinger bosons formalism in a mean field approximation we have investigated the ferroquadrupolar phase of the S=1 Heisenberg model with bilinear and biquadratic exchange interactions on the square lattice. This nonmagnetic phase is characterized by a finite quadrupole moment. We have compared our results with the ones obtained from other theories.