INCOMMENSURATE-COMMENSURATE TRANSITION VIA DOMAIN-WALL EVAPORATION INAN OVERLAYER

A new mechanism is proposed in a two-dimensional system for the transi tion front an incommensurate phase containing walls of striped symmetr y to a commensurate phase via evaporation of the domain walls into a g as 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 densit y. The incommensurate-commensurate transition via domain wall evaporat ion (DWE transition) occurs under the condition of fixed overlayer cov erage, and can be of either first or second order. We study the possib le types of the phase diagram in the case of DWE. Experimental example s are discussed. In the case of the second-order DWE transition the do main wall density rho(w) behaves near T-c like rho(w) proportional to (T-c - T).