Electronic states and magnetism of monatomic Co and Cu wires

The electronic structure of monatomic Cu and Co wires grown by step decoration of the vicinal Pt~997! surface has been investigated by angle-resolved photoemission with synchrotron radiation. Sensitivity to the small amount ~'0.1 monolayer! of deposited material that forms the one-dimensional wires could be achieved at photon energies close to the Pt 5d Cooper minimum, where the photoemission cross section of the substrate valence band is strongly reduced. A single photoemission feature is associated with the 3d emission from the Cu monatomic wire. A double-peaked 3d structure is instead observed for Co wires, suggesting the presence of a one-dimensional exchange-split band and of local magnetic moments.