Solid-liquid transition in 2D dipolar systems

¹ Institut des NanoSciences de Paris, UMR 7588-CNRS, Universités Paris 6 & Paris 7 Campus Boucicaut, 75015 Paris, France
² Laboratoire MPQ UMR 7162-CNRS, Université Paris 7, case 7020 2 place Jussieu, 75251 Paris, France

Received: 17 November 2005
Accepted: 23 February 2006

Abstract

The solid-liquid phase diagram of two-dimensional, laterally confined systems made of interacting parallel dipoles normal to the plane is investigated by Monte Carlo method. The lowest-energy solid phase is relaxed from a regular triangular lattice. This Wigner crystal phase keeps the main features of the original monocrystal. On the other hand, the solid phase relaxed from a random initial configuration has a slightly higher energy and is called Wigner glass. It exhibits randomly oriented crystallites separated by chains of topological defects, namely alternate 5- and 7-nearest-neighbour sites. These chains start to move within the solid phase at a temperature lower than the bulk melting temperature.