Two-Dimensional Melting in a Coulomb Crystal of Dusty Plasmas

Abstract

Two-dimensional melting was observed in a simple hexagonal Coulomb crystal of dusty plasmas. When gas pressure was increased, the particle arrangement of crystalline structure changed from the ordered to the disordered phase. In the change, translational and bond-orientational orders of the arrangement were disturbed. On the other hand, Monte Carlo simulation was employed to examine the experimental results. In the Yukawa system observed in the simulation, where the interaction between the charged particles became weaker, the translational order became short range at first. After that, the bond-orientational order also became short range. According to both experimental and simulation results, melting transition was induced by decreasing the Coulomb interaction between particles with increasing pressure in the laboratory dusty plasma. The dynamics of two-dimensional Coulomb crystals, especially two-dimensional melting, was partly clarified in this work.