Incommensurate-commensurate transition via domain wall evaporation in an overlayer

¹ Institut für Festkörperphysik, Universität Hannover Appelstraße 2, D-30167, Hannover, Germany
² Institut für Theoretische Physik, Universität Hannover Appelstraße 2, D-30167, Hannover, Germany

Received: 17 July 1995
Accepted: 2 February 1996

Abstract

A new mechanism is proposed in a two-dimensional system for the transition from an incommensurate phase containing walls of striped symmetry to a commensurate phase via evaporation of the domain walls into a gas of point-like defects (PD). The point-like defect can be a vacancy, interstitial or a composite defect like domain wall loop. The precise nature of the PD is not important in the limit of vanishing DW density. The incommensurate-commensurate transition via domain wall evaporation (DWE transition) occurs under the condition of fixed overlayer coverage, and can be of either first or second order. We study the possible types of the phase diagram in the case of DWE. Experimental examples are discussed. In the case of the second-order DWE transition the domain wall density behaves near T_c like .