The dynamics of linarite: Observations of magnetic excitations

TL;DR

This study uses inelastic neutron scattering to investigate magnetic excitations in linarite, revealing low-energy spin wave dispersions and quantifying interchain couplings, while analyzing data with theoretical models to determine the magnetic Hamiltonian.

Contribution

First combined experimental and theoretical analysis of magnetic excitations in linarite, establishing its key exchange interactions and realistic Hamiltonian.

Findings

Low-energy dispersive spin wave excitations observed below 1.5 meV.

Interchain couplings are approximately 10% of intrachain interactions.

Main magnetic exchange interactions and Hamiltonian identified.

Abstract

Here we present inelastic neutron scattering measurements from the frustrated, quantum spin-1/2 chain material linarite, PbCuSO_4(OH)_2. Time of flight data, taken at 0.5K and zero applied magnetic field reveals low-energy dispersive spin wave excitations below 1.5meV both parallel and perpendicular to the Cu-chain direction. From this we confirm that the interchain couplings within linarite are around 10% of the nearest neighbour intrachain interactions. We analyse the data within both linear spin-wave theory and density matrix renormalisation group theories and establish the main magnetic exchange interactions and the simplest realistic Hamiltonian for this material.