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.