Dynamics of linarite: Observations of magnetic excitations

Abstract

Here we present inelastic neutron scattering measurements from the frustrated, quantum spin-1/2 chain material linarite, ${\mathrm{PbCuSO}}_{4}{(\mathrm{OH})}_{2}$. Time of flight data, taken at 0.5 K and zero applied magnetic field reveals low-energy dispersive spin wave excitations below 1.5 meV 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 neighbor intrachain interactions. We analyze the data within both linear spin-wave theory and density matrix renormalization group theories and establish the main magnetic exchange interactions and the simplest realistic Hamiltonian for this material.