Estimates of the thermal-to-percolation crossover exponent in the transition to ferromagnetism induced by Ni impurities in Cu and Pd

An analysis of previously acquired data on the concentration dependence of the paramagnetic to ferromagnetic critical temperature, T-c(p), for the CuN i and PdNi systems (i) indicates that the T-c(p) are consistent with the pr edictions of percolation theory, viz. T-c(p) proportional to (p - p(c))(phi ), (ii) provides a first estimate of the thermal-to-percolation crossover e xponent phi for these systems, showing it to be consistent with Heisenberg model predictions, and (iii) confirm earlier estimates for the percolation thresholds, p(c), obtained from other data. (C) 2000 Elsevier Science Ltd, All rights reserved.