Inelastic neutron scattering measurement of the temperature dependence of excitation linewidths in a one-dimensional antiferromagnet

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Abstract
An investigation of the effective linewidth of the spin-wave-like excitations in a one-dimensional magnetic system with antiferromagnetic Heisenberg interactions between the ions, (CD3)4NMnCl3 (TMMC), has been carried out using inelastic neutron scattering. Measurements have been made over the temperature range 4.3-20K, representing 0.6 TMF to 0.26 TMF where TMF is the molecular field transition temperature (75K), and at reduced wavevectors q* of 0.20 pi /d and 0.25 pi /d where d is the spacing between the magnetic ions. The data show that the effective linewidth, Delta , varies as Delta =ATalpha , where A=0.093(+or-0.02) MeV and 0.084(+or-0.02) MeV, and alpha =0.88(+or-0.10) and 0.97(+or-0.10), for the two values of q* respectively. There is very little renormalization of the peak energies.