Optimization and self-organized criticality in a magnetic system

We propose a kind of Bak–Sneppen dynamics as a general optimization technique to treat 9 magnetic systems. The resulting dynamics shows self-organized criticality with power-law scaling of the spatial and temporal correlations. An alternative method of the extremal optimization (EO) 11 is also analyzed here. We provided a numerical con3rmation that, for any possible value of its free parameter , the EO dynamics exhibits a non-critical behavior with an in3nite spatial range 13 and exponential decay of the avalanches. Using the chiral clock model as our test system, we compare the e5ciency of the two dynamics with regard to their abilities to 3nd the system’s 15 ground state. c © 2002 Published by Elsevier Science B.V. 17 PACS: 05.65.+b; 75.10.Hk; 02.60.Pn; 64.60.Cn