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Here we study the two-dimensional Kaya-Berker model, with a site occupancy p of one sub lattice, by using a polynomial-time exact ground-state algorithm. Thus, we were able to obtain T=0 results in exact equilibrium for rather large system sizes up to 777^2 lattice sites. We obtained sub-lattice magnetization and the corresponding Binder parameter. We found a critical point p_c=0.6423(3) beyond which the sub-lattice magnetization vanishes. This is clearly smaller than previous results which were obtained by using non-exact approaches for much smaller systems. We also created for each realization minimum-energy domain walls from two ground-state calculations for periodic and anti-periodic boundary conditions, respectively. The analysis of the mean and the variance of the domain-wall distribution shows that there is no thermodynamic stable spin-glass phase, in contrast to previous claims about this model., Comment: 7 pages, 10 figures

We studied the nonequilibrium aging behavior of the Random Field Ising Model in three dimensions for various values of the disorder strength. This allowed us to investigate how the aging behavior changes across the ferromagnetic-paramagnetic phase transition. We investigated a large system size of $N=256^3$ spins and up to $10^8$ Monte Carlo sweeps. To reach these necessary long simulation times we employed an implementation running on Intel Xeon Phi coprocessors, reaching single spin flip times as short as 6 ps. We measured typical correlation functions in space and time to extract a growing length scale and corresponding exponents., Comment: 8 pages, 13 figures, code available at https://github.com/svonohr/rfim_phi