Critical properties in two-dimensional order-disorder phase transitions: experimental determination of the exponents alpha and eta by integrating methods
Institut für Festkörperphysik, Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany
Accepted: 13 March 1997
Integrating methods in low-energy electron diffraction (LEED) —turning the instrument to low resolution in — can reliably be used to study critical properties of continuous two-dimensional phase transitions and to determine critical exponents α and η. We performed systematic tests of the conditions under which an energy-like power dependence of the diffracted intensity of superstructure beams can be observed in order-disorder phase transitions of adsorbed atomic layers belonging to 3- and 4-state Potts universality classes. We further show that in the limit the exponent η can be determined reliably both below and above Tc using integrated intensities.
PACS: 05.70.Jk – Critical point phenomena / 68.35.Rh – Phase transitions and critical phenomena
© EDP Sciences, 1997