Dynamics of a distorted diamond chain

We present results on the dynamics of the distorted diamond chain, S=1∕2 dimers alternating with single spins 1∕2 and exchange couplings J₁ and J₃ in between. The dynamics in the spin fluid (SF) and tetramer-dimer (TD) phases is investigated numerically by exact diagonalization for up to 24 spins. Representative excitation spectra are presented both for zero magnetic field and in the 1∕3 plateau phase and the relevant parameters are determined across the phase diagram. The behavior across the SF-TD phase transition line is discussed for the specific heat and for excitation spectra. The relevance of the distorted diamond chain model for the Cu₃(CO₃)₂(OH)₂ (azurite) material is discussed with particular emphasis on inelastic neutron scattering experiments; the recent suggestion of one possibly ferromagnetic coupling constant is not confirmed.