Fluctuations and phase separation in Br/Pt(110)

摘要

The quasi-one-dimensional system c(2×2)-Br/Pt(110) is investigated by low-energy electron diffraction (LEED) spot-profile analysis and by variable-temperature scanning tunnelling microscopy (VT-STM). An order-disorder transition is found at 375 K. For 250 K < T < 375 K a long-range ordered c(2×2) phase is observed, but the spot profiles reveal strong correlated fluctuations along the close-packed row direction. At T= 50 K three different phases coexist in a glassy state: c(2×2), (2×1), and (3×2). The loss of long-range order and transition into a phase-separated state is a common feature predicted for strongly correlated systems. Some inconsistencies between theory and experiment in our previous interpretation of the (3×1)-Br/Pt(110) phase as a charge density wave (CDW) are resolved by identifying it as a fluctuating (3×2) CDW phase.