Phase diagram of an anisotropic frustrated ferromagnetic spin-1/2 chain in a magnetic field: a density matrix renormalization group study

TL;DR

This study maps the phase diagram of an anisotropic frustrated ferromagnetic spin-1/2 chain in a magnetic field using DMRG, revealing how anisotropy influences bound states, chiral phases, and quantum phase transitions relevant to LiCuVO4.

Contribution

It provides the first detailed phase diagram of the anisotropic frustrated spin-1/2 chain in a magnetic field using DMRG, highlighting the effects of anisotropy on phase stability and transitions.

Findings

Easy-axis anisotropy promotes multimagnon bound states.

Easy-plane anisotropy favors chiral order.

Moderate easy-plane anisotropy induces a quantum phase transition.

Abstract

We study the phase diagram of a frustrated spin-1/2 ferromagnetic chain with anisotropic exchange interactions in an external magnetic field, using the density matrix renormalization group method. We show that an easy-axis anisotropy enhances the tendency towards multimagnon bound states, while an easy-plane anisotropy favors chirally ordered phases. In particular, a moderate easy-plane anisotropy gives rise to a quantum phase transition at intermediate magnetization. We argue that this transition is related to the finite-field phase transition experimentally observed in the spin-1/2 compound LiCuVO_4.