Critical Lines and Massive Phases in Quantum Spin Ladders with Dimerization

TL;DR

This paper maps the phase diagram of dimerized quantum spin ladders, identifying critical lines and characterizing massive phases using DMRG and string order parameters, revealing dependence on dimerization patterns and coupling types.

Contribution

It introduces a comprehensive analysis of critical lines and massive phases in various dimerized spin ladder configurations using advanced numerical methods.

Findings

Critical lines depend on dimerization pattern and coupling type.

Massive phases are characterized by valence bond solid content.

Finite-size DMRG effectively maps phase boundaries.

Abstract

We determine the existence of critical lines in dimerized quantum spin ladders in their phase diagram of coupling constants using the finite-size DMRG algorithm. We consider both staggered and columnar dimerization patterns, and antiferromagnetic and ferromagnetic inter-leg couplings. The existence of critical phases depends on the precise combination of these patterns. The nature of the massive phases separating the critical lines are characterized with generalized string order parameters that determine their valence bond solid (VBS) content.