Speaker
Description
The spin-1 XXZ chain with uniaxial single-ion anisotropy exhibits a rich ground-state phase diagram, hosting topologically distinct Haldane and large-D phases alongside various magnetically ordered and gapless phases. In 1986, H. J. Schulz formulated an effective field theory for this system by mapping it onto coupled spin-1/2 chains (i.e., a ladder) and derived its phase diagram via bosonization and perturbative renormalization group (RG) techniques. While Schulz's results qualitatively agree with subsequent numerical studies of the spin-1 chain, it remains unclear how the phase structure of the anisotropic ladder evolves from the weak-interchain-coupling regime, where perturbative RG is most reliable, to the strong-coupling point that recovers the true spin-1 chain. In this study, we numerically investigate the evolution of the phase diagram across the full range of interchain coupling. We demonstrate that the qualitative features of the phase diagram are preserved throughout this evolution, confirming the robustness of Schulz's framework. However, we also highlight the critical role of competing magnetic phases unique to the ladder geometry.