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DY: Dynamik und Statistische Physik

DY 40: Lyapunov Instability of Many-Body Systems

DY 40.6: Vortrag

Donnerstag, 11. März 2004, 11:00–11:15, H2

Short-range type critical behavior in spite of long-range interactions: phase transition of a Coulomb system on a lattice — •Arnulf Möbius and Ulrich K. Rößler — Leibniz-Institut für Festkörper- und Werkstoffforschung, D-01171 Dresden

The problem under which conditions Coulomb glasses exhibit genuine phase transitions has been under controversial debate for a long time,see e.g. [1,2]. In this context, the relation to the Ising model with short-range interaction is of great interest. It would be very useful to know how replacing its nearest-neighbor coupling by an “antiferromagnetic” long-range Coulomb interaction modifies the critical behavior of a system without static disorder.

One- to three-dimensional hypercubic lattices half-filled with localized particles interacting via a Coulomb potential are investigated numerically. Temperature dependences of specific heat, mean staggered occupation, and of a generalized susceptibility indicate order-disorder phase transitions in two- and three-dimensional systems. The critical properties, clarified by finite-size scaling analysis, are consistent with those of the Ising model with short-range interaction [3]. Thus, in spite of the long-range interaction, the Coulomb system considered seems to belong to the same universality class as the Ising model with short-range interaction. This suggests that the lattice Coulomb-glass model might have the same critical properties as the random-field short-range Ising model.

[1] E.R. Grannan, C.C. Yu, Phys. Rev. Lett. 71, 3335 (1993).

[2] T. Vojta, M. Schreiber, Phys. Rev. Lett. 73, 2933 (1994).

[3] A. Möbius and U.K. Rößler, cond-mat/0309001.