Neutron Scattering Study of Magnetic Excitations in Quasi-One-Dimensional Triangular Lattice Antiferromagnet CsVCl3

CsVCl 3 is composed of one-dimensional antiferromagnetic chains which are coupled weakly antiferromagnetically in the basal hexagonal plane. In order to clarify the anomalous properties hitherto observed, an inelastic neutron scattering has been studied. We observed good one-dimensionality of J '/ J =2.7×10 -4 . But, though S =3/2, the spin wave dispersion along the chain disagrees with the classical picture. The excitation spectra along the triangular lattice plane are unusual. The excitation is dominated by a dispersionless mode of strong intensity. Compared to this mode, the conventional acoustic spin wave branch seems to be of minor excitation at lower temperatures than the Néel point.