Melting of different shape 2d electron clusters

Melting of two-dimensional clusters is studied by molecular dynamics method. The clusters can be created in the electron systems over superfluid helium with holding electrodes of triangular, square, hexagonal, and round shape. The surface electron density ns = 108 cm-2 is fixed. The clusters studied contain from 3 to 406 electrons. The transition to a non-ordered state for the defect-free clusters is shown to occur sharply and the melting temperature melt can be found easily. The melt dependence on cluster size is observed for the clusters containing less than 400 particles (N 100 one can see the triangular lattice with defects near the edge of the cluster. In the round clusters electrons can move easily in the angular direction even at enough low temperatures, but the temperature of the radial melting agrees with the melting temperature of the small square clusters. The transition to a non-ordered state for clusters with defects starts near the defect and spread gradually over the whole cluster. In this case, there is no clear definition of the melting point. © 2020 Institute for Low Temperature Physics and Engineering. All rights reserved.