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

We study numerically various properties of the free energy barriers in the Edwards–Anderson model of spin glasses in the low-temperature region in both 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 3D 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 Dlc = 2.5 as the lower critical dimension of the model.