Critical behavior and 1/f noise in lumped systems undergoing two phase transitions

It is shown that the interaction of order parameters when subcritical and s upercritical phase transitions take place simultaneously may result in a se lf-organized critical state and cause a 1/f (alpha) fluctuation spectrum, w here 1 less than or equal to alpha less than or equal to 2. Such behavior i s inherent in potential and nonpotential systems of nonlinear Langevin equa tions. A numerical analysis of the solutions to the proposed systems of sto chastic differential equations showed that the solutions correlate with fra ctional integration and differentiation of white noise. The general behavio r of such a system has features in common with self-organized criticality. (C) 2000 MAIK "Nauka/Interperiodica".