Alternating Heisenberg Spin-1/2 Chains in a Transverse Magnetic Field

TL;DR

This paper investigates the phase diagram of alternating spin-1/2 chains with anisotropic ferromagnetic coupling in a transverse magnetic field, identifying quantum phase transitions and magnetic phases using exact diagonalization.

Contribution

It provides the first detailed analysis of the critical fields and phase transitions in this specific spin chain model with a transverse magnetic field.

Findings

Identified two Ising-type quantum phase transitions.

Calculated critical magnetic fields $h_{c_{1}}$ and $h_{c_{2}}$.

Discovered an intermediate gapful stripe-antiferromagnetic phase.

Abstract

The ground state phase diagram of the alternating spin-1/2 chains with anisotropic ferromagnetic coupling under the influence of a symmetry breaking transverse magnetic field is studied. We have used the exact diagonalization technique. In the limit where the antiferromagnetic coupling is dominant, we have identified two Ising-type quantum phase transitions. We have calculated two critical fields $h_{c_{1}}$ and $h_{c_{2}}$, corresponding to the transition between different magnetic phases of the system. It is found that the intermediate state ($h_{c_{1}}<h<h_{c_{2}}$) is gapful, describing the stripe-antiferromagnetic phase.