The phase diagram of magnetic ladders constructed from a composite-spin model

TL;DR

This paper uses DMRG to analyze a composite-spin ladder model, revealing multiple massive phases and how the energy gap varies with different coupling constants, bridging models with different spin lengths.

Contribution

It introduces a composite-spin ladder model analyzed with DMRG, showing the existence of multiple massive phases and continuous interpolation between models.

Findings

Multiple massive phases identified

Energy gap behavior mapped across parameter space

Model interpolates between different spin length systems

Abstract

White's density matrix renormalization group ({DMRG}) method has been applied to an $S= 1/2 + 1/2$ composite-spin model, which can also be considered as a two-leg ladder model. By appropriate choices of the coupling constants this model allows not only to study how the gap is opened around the gapless integrable models, but also to interpolate continuously between models with different spin lengths. We have found indications for the existence of several different massive phases.