Surface phase diagram and temperature induced phase transitions of Sn/Cu(1 0 0)

Room temperature deposition of Sn on Cu(1 0 0) gives rise to a rich variety of surface reconstructions in the submonolayer coverage range. In this work, we report a detailed investigation on the phases appearing and their temperature stability range by using low-energy electron diffraction and surface X-ray diffraction. Previously reported reconstructions in the submonolayer range are p(2 2) (for 0.2 ML), p(2 6) (for 0.33 ML), (3 ffiffiffi 2 p ffiffiffi 2 p )R458 (for 0.5 ML), and c(4 4) (for 0.65 ML). We find a new phase with a 4 2 0 4 structure for a coverage of 0.45 ML. Furthermore, we analyze the temperature stability of all phases.We find that two phases exhibit a temperature induced reversible phase transition: the (3 ffiffiffi 2 p ffiffiffi 2 p )R458 phase becomes ( ffiffiffi 2 p ffiffiffi 2 p )R458 phase above 360 K, and the new 4 2 0 4 phase becomes p(2 2) also above 360 K. The origin of these two-phase transitions is discussed.