Large-scale Monte Carlo simulations for the depinning transition in Ising-type lattice models

With the developed “extended Monte Carlo” (EMC) algorithm, we have studied the depinning transition in Ising-type lattice models by extensive numerical simulations, taking the random-field Ising model with a driving field and the driven bond-diluted Ising model as examples. In comparison with the usual Monte Carlo method, the EMC algorithm exhibits greater efficiency of the simulations. Based on the short-time dynamic scaling form, both the transition field and critical exponents of the depinning transition are determined accurately via the large-scale simulations with the lattice size up to L=8912, significantly refining the results in earlier literature. In the strong-disorder regime, a new universality class of the Ising-type lattice model is unveiled with the exponents β=0.304(5),ν=1.32(3),z=1.12(1), and ζ=0.90(1), quite different from that of the quenched Edwards-Wilkinson equation.