  Realisation of the tetragonal phase of $Cs_2CuCl_4$ 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
$Cs_2CuCl_{2.9}Br_{1.1}$, $Cs_2CuCl_{2.5}Br_{1.5}$, $Cs_2CuCl_{2.2}Br_{1.8}$
and presents consistent results for such quasi $2-D$ antiferromagnets.
Structural investigation at low temperature for $Cs_2CuCl_{2.2}Br_{1.8}$ shows
no phase transition. The structure remains in the tetragonal symmetry $I4/mmm$.
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.
