Real space investigation of the roughening and deconstruction transitions of Au(110)

As established by diffraction techniques Au(110)-(1 x 2), which is missing-row reconstructed at 300 K, consecutively undergoes two phase transitions upon heating: an Ising transition at approximate to 650 K and a 3D roughening transition at approximate to 700 K. Our teal space investigation with atomic scale resolution by temperature-variable scanning tunneling microscopy reveals that-contrary to present theoretical models-the Ising transition is due to antiphase domains developing during the 2D roughening of (1 x 3) steps. The missing-row configuration of interior terrace regions remains completely stable until the 3D roughening temperature, thus ruling out an order-disorder transition via lattice gas formation.