Phase Diagrams of S=3/2, 2 XXZ Spin Chains with Bond-Alternation

TL;DR

This paper investigates the phase diagrams of higher-spin (S=3/2 and 2) bond-alternating XXZ spin chains, revealing complex phase structures linked to hidden symmetries, using advanced numerical methods.

Contribution

It provides the first detailed numerical analysis of the phase diagrams for S=3/2 and 2 spin chains, connecting their phase structures to hidden $Z_{2} imes Z_{2}$ symmetry.

Findings

Phase diagrams of S=3/2 and 2 chains are mapped.

Phase structures relate to hidden $Z_{2} imes Z_{2}$ symmetry.

Higher S chains show more complex phase transitions.

Abstract

We study the phase diagram of S=3/2 and S=2 bond-alternating spin chains numerically. In previous papers, the phase diagram of S=1 XXZ spin chain with bond-alternation was shown to reflect the hidden $Z_{2}\times Z_{2}$ symmetry. But for the higher S Heisenberg spin chain, the successive dimerization transition occurs, and for anisotropic spin chains the phase structure will be more colorful than the S=1 case. Using recently developed methods, we show directly that the phase structure of the anisotropic spin chains relates to the $Z_{2}\times Z_{2}$ symmetry.