Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Finite size effects at phase transitions I (session accompanying the symposium of the same name)

DY 19.3: Vortrag

Dienstag, 27. März 2007, 17:30–17:45, H2

Finite-size scaling of droplets in two-dimensional ±J Ising spin glasses — •Alexander Hartmann — Institut für Theoretische Physik, Universität Göttingen, Germany

The behavior of two-dimensional Ising spin glasses is currently heavily discussed. Of particular interest is the question whether the low-temperature behavior close to the T=0 phase transition depends on the type of disorder, i.e. Gaussian vs. bimodal (±J) distribution. From the finite-size scaling behavior of domain walls previously obtained via ground-state (GS) calculations, it appears that both classes behave differently, while recent Monte Carlo (MC) simulations claim universality. Here, the finite-size scaling of droplet excitations, which are dominating the low-temperature behavior, is studied numerically using a combination of suitable perturbations of the realizations together with exact GS calculations. The GS calculations are based on a matching approach, which allows to treat large system sizes up to N=256×256 spins. The main result is that the finite-size scaling behavior of the droplets is different from the domain-wall scaling, but similar to the scaling of droplets for the Gaussian model. Hence, this could explain the results observed in MC simulations.