Magnetic excitations in a bond-centered stripe phase: Spin waves far from the semi-classical limit

TL;DR

This paper models magnetic excitations in a bond-centered stripe phase using a spin-only approach, successfully explaining neutron scattering data and revealing complex spin dynamics beyond classical descriptions.

Contribution

It introduces a bond operator formalism to compute spin excitation spectra in a bond-centered stripe state, capturing both dimerization and broken symmetry in a unified way.

Findings

Spin excitations resemble spin waves at low energies.

High-energy excitations are similar to spin-1 excitations of spin ladders.

Theory matches neutron scattering data on LaBaCuO.

Abstract

Using a spin-only model, we compute spin excitation spectra in a bond-centered stripe state with long-range magnetic order. We employ a bond operator formalism, which naturally captures both dimerization and broken spin symmetry in a unified framework. At low energies, the spin excitations resemble spin waves, but at higher energies they are very similar to spin-1 excitations of isolated spin ladders. Our theory does well describe neutron scattering data [J. M. Tranquada et al., Nature 429, 534 (2004)] on LaBaCuO, pointing towards bond order in this material.