Ferromagnetic frustrated spin systems on the square lattice: a Schwinger boson study

TL;DR

This study investigates a frustrated ferromagnetic spin system on a square lattice using Schwinger boson mean field theory, revealing shifts in phase boundaries due to quantum fluctuations but no clear spin gap phases.

Contribution

It applies Schwinger boson mean field theory to analyze phase boundaries in a frustrated ferromagnetic square lattice system, highlighting quantum effects.

Findings

Quantum fluctuations shift phase boundaries to smaller J_2 for ferromagnetic to collinear transition.

Boundaries between collinear and incommensurate phases are shifted to larger J_2/|J_1| ratios.

No clear evidence of spin gapped phases within the approximation.

Abstract

We study a ferromagnetic Heisenberg spin system on the square lattice, with nearest neighbors interaction J_1 frustrated by second J_2 and third J_3 neighbors antiferromagnetic interactions, using a mean field theory for the Schwinger boson representation of spins. For J_3=0 we find that the boundary between the ferromagnetic and the collinear classical phases shifts to smaller values of J_2 when quantum fluctuations are included. Along the line J_2/|J_1|= 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.