FERROMAGNETIC FRUSTRATED SPIN SYSTEMS ON THE SQUARE LATTICE: A SCHWINGER BOSON STUDY

H. FELDNER; D.C. CABRA; G.L. ROSSINI

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2011 vol. 84 p. 214406 - 214412

1098-0121

We study a ferromagnetic Heisenberg spin system on the square lattice, with nearest-neighbor interaction J1 frustrated by second,J2, and third, J3, neighbor antiferromagnetic interactions, using a mean-field theory for the Schwinger boson representation of spins. For J3=0 we find that the boundary between the ferromagnetic and the collinear classical phases shifts to smaller values of J2 when quantum fluctuations are included. Along the line |J|=1 the boundaries between the collinear and incommensurate regions are strongly shifted to larger values with respect to the classical case. We do not find clear evidence for spin-gapped phases within the present approximation.