Phase diagram of S=1/2 XXZ chain with NNN interaction

TL;DR

This paper investigates the phase diagram of the S=1/2 XXZ chain with next-nearest neighbor interactions, revealing a direct transition between ferromagnetic and dimerized phases, including effects of bond alternation.

Contribution

It provides new insights into the phase transitions in the XXZ chain with NNN interactions, highlighting a direct ferromagnetic to dimerized phase transition.

Findings

Direct transition between ferromagnetic and dimerized phases

Effect of bond alternation on phase boundaries

Identification of quantum nonmagnetic phase

Abstract

We study the ground state properties of one-dimensional XXZ model with next-nearest neighbor coupling alpha and anisotropy Delta. We find the direct transition between the ferromagnetic phase and the spontaneously dimerized phase. This is surprising, because the ferromagnetic phase is classical, whereas the dimer phase is a purely quantum and nonmagnetic phase. We also discuss the effect of bond alternation which arises in realistic systems due to lattice distortion. Our results mean that the direct transition between the ferromagnetic and spin-Peierls phase occur.