Neutron scattering study of a one-dimensionalXYantiferromagnetCs2CoCl4

The magnetic behavior of ${\mathrm{Cs}}_2$Co${\mathrm{Cl}}_4$ is studied by quasielastic neutron scattering techniques. The one-dimensional (1D) character along the orthorhombic $b$ axis is established by the observation of a sheetlike structure in the static correlation function $S\left(\overrightarrow{\mathrm{Q}}\right)$. The temperature dependence of the inverse correlation length $\kappa \sim \frac{0.88k_{B}T}{\mathrm{}\left|J\right|\mathrm{}}$ between 0.32 and 0.65 K is consistent with the recent theoretical calculation of the $\kappa$ for the in-plane component of spins in a $1\mathrm{D}\mathrm{XY}$ system with $S=\frac{1}{2}$. In addition, the modulation of the 1D sheet of $S\left(\overrightarrow{\mathrm{Q}}\right)$ was found in the paramagnetic phase. With a basis on a simplified model of competing interactions we show that the 1D short-range order is driven to an incommensurate state due to the interchain exchange interactions.