Tetragonal mixed system $C{s}_{2}CuC{l}_{4-x}B{r}_x$ complemented by the tetragonal phase realisation of $C{s}_{2}CuC{l}_4$

Realisation of the tetragonal phase of $C{s}_{2}CuC{l}_4$ is possible using specific crystal growth conditions at a temperature below $281K$. This work deals with the comparison of the magnetic susceptibility and the magnetization of this new tetragonal compound with the magnetic behaviour of tetragonal $C{s}_{2}CuC{l}_{2.9}B{r}_{1.1}$, $C{s}_{2}CuC{l}_{2.5}B{r}_{1.5}$, $C{s}_{2}CuC{l}_{2.2}B{r}_{1.8}$ and presents consistent results for such quasi $2-D$ antiferromagnets. Structural investigation at low temperature for $C{s}_{2}CuC{l}_{2.2}B{r}_{1.8}$ shows no phase transition. The structure remains in the tetragonal symmetry $I4\mathrm{/}mmm$. Furthermore, several magnetic reflections corresponding to the propagation vector $k=(0,0,0)$ are observed for this tetragonal compound through neutron diffraction experiments below the magnetic phase transition at $T_N = 11.3K$ confirming its antiferromagnetic nature.