The spin-1/2 anisotropic Heisenberg-chain in longitudinal and transversal magnetic fields: a DMRG study

TL;DR

This study uses DMRG to analyze the low-energy spectrum of an anisotropic spin-1/2 chain under various magnetic fields, revealing that only a staggered transversal field significantly opens a spin gap.

Contribution

First application of DMRG to evaluate the low-energy spectrum of anisotropic spin chains under different magnetic field configurations.

Findings

A staggered transversal field opens a substantial spin gap.

Homogeneous fields do not open a significant gap.

The low-energy spectrum is sensitive to the type of magnetic field applied.

Abstract

Using the density matrix renormalization group technique, we evaluate the low-energy spectrum (ground state and first excited states) of the anisotropic antiferromagnetic spin-one-half chain under magnetic fields. We study both homogeneous longitudinal and transversal fields as well as the influence of a transversal staggered field on opening of a spin-gap. We find that only a staggered transversal field opens a substantial gap.