Symmetric and asymmetric excitations of a strong-leg quantum spin ladder

TL;DR

This study investigates the excitation spectrum of a strong-leg quantum spin ladder using neutron scattering and compares it with theoretical models, revealing how excitations evolve with varying coupling ratios.

Contribution

It provides a detailed experimental and theoretical analysis of symmetric and asymmetric excitations in a strong-leg spin ladder, including the evolution of two-magnon bound states.

Findings

Decomposition of excitation spectrum into symmetric and asymmetric parts.

Comparison of experimental data with density matrix renormalization group results.

Demonstration of excitation evolution across different coupling regimes.

Abstract

The zero-field excitation spectrum of the strong-leg spin ladder (C$_7$H$_10$N)$_2$CuBr$_4$ (DIMPY) is studied with a neutron time-of-flight technique. The spectrum is decomposed into its symmetric and asymmetric parts with respect to the rung momentum and compared with theoretical results obtained by the density matrix renormalization group method. Additionally, the calculated dynamical correlations are shown for a wide range of rung and leg coupling ratios in order to point out the evolution of arising excitations, as e.g. of the two-magnon bound state from the strong to the weak coupling limit.