Authors Referees APS Members |
January 2008, to be published in Physical Review B1
Structural phase transitions in low-dimensional ion crystals
A chain of singly-charged particles, confined by a harmonic potential, exhibits a sudden transition to a zigzag configuration when the radial potential reaches a critical value, depending on the particle number. This structural change is a phase transition of second order, whose order parameter is the crystal displacement from the chain axis. We study analytically the transition using Landau theory and find full agreement with numerical predictions by J. Schiffer [Phys. Rev. Lett. {\bf 70}, 818 (1993)] and Piacente {\it et al} [Phys. Rev. B {\bf 69}, 045324 (2004)]. Our theory allows us to determine analytically the system's behaviour at the transition point. © 2008 The American Physical Society.
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