ANOMALOUS POWER-LAW ORDERING KINETICS OF PB ON NI(001)

We apply high-resolution x-ray diffraction to study the development of the c(2 x 2) phase of Pb on Ni(001). We observe line shapes in agreement with the scaling theory of Ohta, Jasnow, and Kawasaki, but with an anomalously slow time dependence of average domain size R on time t, R is-proportional-to t0.13. The presence of 1%-3% carbon on the surface acts to slow the growth of order. We are able to understand the observed power-law dependence and the observed effect of C density in an adaptation of the analysis of the random-field Ising model given by Grinstein and Fernandez.