The dynamics of linarite: Observations of magnetic excitations
  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. 
K. C. Rule, B. Willenberg, M. Sch\"apers, A. U. B. Wolter, B.   B\"uchner, S.-L. Drechsler, G. Ehlers, D. A. Tennant, R. A. ...
cond-mat.str-el