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Enhanced stability of the square lattice of a classical bilayer Wigner crystal

I. V. Schweigert·V. A. Schweigert·F. M. Peeters
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Abstract

The stability and melting transition of a single layer and a bilayer crystal consisting of charged particles interacting through a Coulomb or a screened Coulomb potential is studied using the Monte-Carlo technique. A new melting criterion is formulated which we show to be universal for bilayer as well as for single layer crystals in the case of (screened) Coulomb, Lennard--Jones and 1/r^{12} repulsive inter-particle interactions. The melting temperature for the five different lattice structures of the bilayer Wigner crystal is obtained, and a phase diagram is constructed as a function of the interlayer distance. We found the surprising result that the square lattice has a substantial larger melting temperature as compared to the other lattice structures. This is a consequence of the specific topology of the defects which are created with increasing temperature and which have a larger energy as compared to the defects in e.g. a hexagonal lattice.

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I. V. Schweigert, V. A. Schweigert, F. M. Peeters. 1999-08-18. Enhanced stability of the square lattice of a classical bilayer Wigner crystal. https://doi.org/10.1103/physrevb.60.14665

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