Surface reconstruction of FeAl(110) studied by scanning tunnelling microscopy and angle-resolved photoemission spectroscopy
Orhan Kizilkaya, Dustin A. Hite, David M. Zehner, Phillip T. Sprunger
The surface geometric and electronic structure of the FeAl(110) intermetallic alloy has been investigated by scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES). Preferential sputtering results in a depletion of Al in the near surface region and subsequent annealing promotes surface segregation of Al and gives rise to new reconstructed phases. A bulk terminated surface structure is obtained after annealing the surface to 400 °C. However, an incommensurate phase develops in the temperature range of 400-600 °C and above 800 °C with a stoichiometry consistent with a FeAl2 structure in the topmost layer. The ARPES measurements confirm the Al segregation with increased density of states (DOS) at the near Fermi level. The increased DOS is believed to be due to hybridization between the Fe-d and Al-sp states. The increased intensity of the Al-2p core level for the incommensurate phase also confirms the higher Al surface concentration for this phase.