Scanning tunneling microscopy investigation of electronic properties of cobalt nanoislands supported by Cu–9at.%Al(111)

Growth and surface electronic states of Co nanoislands supported by Cu–9 at.%Al(111) are investigated by low temperature scanning tunneling microscopy. Deposition of about 0.25 monolayer of Co atoms causes the formation of flat Co nanoislands with thicknesses ranging from monolayer to triple layer. Scanning tunneling spectroscopy measurements reveal that a Tamm-type surface state exists on the Co islands and its energy varies with the thicknesses and stacking manners. In addition, density functional theory calculations conclude that the surface states of the mono- and bilayer nanoislands mainly originate from the hybridization between Co d bands and sp bands of the substrate and the Co d 3 z 2 − r 2 minority-spin bands, respectively.