Support for the value 5/2 for the spin glass lower critical dimension at zero magnetic field

TL;DR

This paper numerically investigates free energy barriers in the Edwards-Anderson spin glass model, providing evidence that the lower critical dimension is 2.5, consistent with mean field theory predictions.

Contribution

It offers numerical support for the value of 2.5 as the lower critical dimension of the spin glass model at zero magnetic field, aligning with mean field theory.

Findings

Barrier heights scale with system size and overlap distance

Distribution of large local fluctuations matches mean field predictions

Supports D_{lc}=2.5 as the lower critical dimension

Abstract

We study numerically various properties of the free energy barriers in the Edwards-Anderson model of spin glasses in the low-temperature region both in three and four spatial dimensions. In particular, we investigated the dependence of height of free energy barriers on system size and on the distance between the initial and final states (i.e. the overlap distance). A related quantity is the distribution of large local fluctuations of the overlap in large three-dimensional samples at equilibrium. Our results for both quantities (barriers and large deviations) are in agreement with the prediction obtained in the framework of mean field theory. In addition, our result supports $D_{lc}=2.5$ as the lower critical dimension for the model.