  The formation and melting of a mono-layered charged dust particle crystal in
a DC glow discharge Argon plasma is studied. The nature of the
melting/formation process is established as a first order phase transition from
the nature of the variations in the Coulomb coupling parameter, the dust
temperature, the structural order parameter and from the existence of a
hysteresis behavior. Our experimental results are distinctly different from
existing theoretical predictions for 2D crystals based on the KTHNY mechanism
or the Grain boundary induced melting and indicate a novel mechanism that is
akin to a fluctuation induced first order phase transition that has not been
observed before in complex plasmas.
