Influence of interchain coupling on the one-dimensional magnon Raman spectrum of CsCoBr3

Light scattering from magnons in CsCoBr₃ has been measured for temperatures well below the upper antiferromagnetic 3D ordering temperature of T^l_N = 28 K. These experiments reveal multiple magnon features of energies in the range 90 to 170 cm^-1 similar to those found in CsCoCl₃ but previously unobserved for the bromide. Prominent features in the spectrum and their temperature dependence are described in terms of a recent theory by Shiba. Other, weaker features are explained by a simple extension of the theory to include fluctuations. A new band is observed at 178 cm^-1, whose intensity drops sharply prior to the lower 3D ordering transition at T^l_N = 10 K. This band is assigned to magnon-phonon combination scattering.