Studying avalanches in the ground state of the two-dimensional random-field ising model driven by an external field
We study the exact ground state of the two-dimensional random-field Ising model as a function of both the external applied field B and the standard deviation sigma of the Gaussian random-field distribution. The equilibrium evolution of the magnetization consists in a sequence of discrete jumps. These are very similar to the avalanche behavior found in the out-of-equilibrium version of the same model with local relaxation dynamics. We compare the statistical distributions of magnetization jumps and find that both exhibit power-law behavior for the same value of sigma. The corresponding exponents are compared.
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Institut de Ciencia de Materials de Barcelona, Consell Superior d'Investigacions Cientifiques, Campus UAB, 08193 Bellaterra, Catalonia, Spain.
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