SCANNING TUNNELING MICROSCOPY OBSERVATION OF PHASE-TRANSITION PHENOMENA IN THE CS/CU(110) SYSTEM - EVIDENCE FOR A 2-STEP DISORDERING MECHANISM OF A UNIAXIAL (1X3) PHASE

The disordering of the uniaxial Cs/Cu(110) (1 x 3) phase was studied by scanning tunneling microscopy as a test case for the theoretical predictions of a two-step disordering mechanism. Lowering the Cs coverage first causes the formation of domain walls in the (1 x 3) phase, indicating a transition from a two-dimensional commensurate solid into an incommensurate floating solid. Dislocations in this wall pattern lead to progressing disordering into an incommensurate fluid. Further coverage reduction stabilizes fluctuating domains of a (1 x 4) phase, which signal a close by continuous solid to fluid transition.