Berlin 2005 – scientific programme

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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.13: Poster

Monday, March 7, 2005, 15:30–18:00, Poster TU D

Scaling of energy barrier in two-dimensional spin glasses — •Carlo Amoruso^1,2, M.A. Moore², and Alexander K. Hartmann¹ — ¹Institut für Theoretische Physik, Friedrich-Hund-Platz 1, 37077 Göttingen — ²Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom

Energy barriers determine the dynamics of glassy systems that have a complex energy landscape with many metastable states, like spin glasses. In the droplet approach a central role is played by an exponent θ which characterizes the energetics of large scale excitation from the ground state. Such excitation scale like as L^θ. The system orders at low temperature if θ > 0. The dynamics is controlled by the rate of creation of those excitations, and it is generally assumed that the barrier against this relaxation scales as L^ψ where θ ≤ ψ ≤ d−1 for dimension d. We study the case of d=2 spin glasses, where θ≈−0.28. We are using an optimization procedure [1], based on combinatorial matching algorithms, and suitable modifications of the disorder [2], which allows us to treat relative large samples. Using this approach, we are able to give the bounds +0.28 < ψ < 0.58.

[1] A.K. Hartmann and H. Rieger, Optimization Algorithms in Physics, Wiley-VCH (2001)

[2] A.K. Hartmann and M.A. Moore, Phys. Rev. Lett. 90, 127201 (2003)