Aspect-ratio scaling and the stiffness exponent theta for Ising spin glasses

We introduce the technique of aspect-ratio scaling to study the scale dependence of interfacial energies in Ising spin glasses, and we show how one can use it to determine the stiffness exponent theta in a clean way, with results that are independent of the domain-wall-forcing boundary conditions imposed on the system. In space dimension d = 2 we obtain theta = -0.282(3) for a Gaussian distribution of exchange interactions.