Spin gap and string order parameter in the ferromagnetic Spiral Staircase Heisenberg Ladder: a quantum Monte Carlo study
Abstract
We consider a spin-1/2 ladder with a ferromagnetic rung coupling J and inequivalent chains. This model is obtained by a twist (θ) deformation of the ladder and interpolates between the isotropic ladder (θ=0) and the SU(2) ferromagnetic Kondo necklace model (θ=π). We show that the ground state in the (θ,J) plane has a finite string order parameter characterising the Haldane phase. Twisting the chain introduces a new energy scale, which we interpret in terms of a Suhl-Nakamura interaction. As a consequence we observe a crossover in the scaling of the spin gap at weak coupling from /J\| J/J\| for θ < θc 8π/9 to /J\| (J/J\|)2 for θ > θc. Those results are obtained on the basis of large scale Quantum Monte Carlo calculations.
Turn this paper into a lesson
ArcXiv compiles a structured reading guide from this paper's metadata: plain-English importance, contributions, prerequisite concepts, which sections to read first, flashcards, and a quiz. Grounded in the abstract, never invented.