M. Michailov et al., Thermal behavior of c(2X2) layers in the Pb/Cu(110) system and the influence of surface defects on the order-disorder transition, PHYS REV B, 61(9), 2000, pp. 5987-5992
The thermal behavior of a c(2X2) Ph overlayer on Cu(110) surface is studied
by thermal energy atom scattering. Diffraction analysis reveals a continuo
us reversible order-disorder transition with temperature at 437+/-2.5 K. Tw
o of the extracted critical exponents, gamma and nu, are in good agreement
with those of the two-dimensional Ising universality class. The third, beta
, associated with the disappearance of long-range order in the layer, is, h
owever, smaller than the theoretical expectations. The observed transition
is discussed in a framework of model, where the deviation of one of the exp
onents beta, gamma, and nu from its exact value depends in a different way
on the kind of "imperfection" (mean terrace width, domain boundaries, "froz
en-in" surface defects, local distortions, and surface alloying) in the rea
l physical system. The annihilation of domain walls, created during the sim
ultaneous growth of c(2X2) phase on two equivalent sublattices of {110} fcc
surface, is found at 310 K. The experimental findings indicate also a noti
ceable change in the surface corrugation during the observed order-disorder
transition.