Quantum phase diagram of an exactly solved mixed spin ladder

TL;DR

This paper analyzes the quantum phase diagram of an exactly solvable mixed spin-(1/2,1) ladder using thermodynamic Bethe ansatz, revealing multiple quantum phases, magnetization plateaux, and phase transitions under varying magnetic fields and couplings.

Contribution

It provides a comprehensive analysis of the phase diagram of a mixed spin ladder model, including the effects of magnetic fields and coupling strengths, using exact solutions.

Findings

Identification of three quantum phases with su(2), su(4), and su(6) symmetries.

Discovery of a full saturation magnetization plateau under strong magnetic fields.

Observation of quantum phase transitions as the magnetic field varies.

Abstract

We investigate the quantum phase diagram of the exactly solved mixed spin-(1/2,1) ladder via the thermodynamic Bethe ansatz (TBA). In the absence of a magnetic field the model exhibits three quantum phases associated with su(2), su(4) and su(6) symmetries. In the presence of a strong magnetic field, there is a third and full saturation magnetization plateaux within the strong antiferromagnetic rung coupling regime. Gapless and gapped phases appear in turn as the magnetic field increases. For weak rung coupling, the fractional magnetization plateau vanishs and exhibits new quantum phase transitions. However, in the ferromagnetic coupling regime, the system does not have a third saturation magnetization plat eau. The critical behaviour in the vicinity of the critical points is also derived systematically using the TBA.