title: Enhanced atom mobility on the surface of a metastable film.
abstract: A remarkable enhancement of atomic diffusion is highlighted by scanning tunneling microscopy performed on ultrathin metastable body-centered tetragonal Co films grown on Fe(001). The films follow a nearly perfect layer-by-layer growth mode with a saturation island density strongly dependent on the layer on which the nucleation occurs, indicating a lowering of the diffusion barrier. Density functional theory calculations reveal that this phenomenon is driven by the increasing capability of the film to accommodate large deformations as the thickness approaches the limit at which a structural transition occurs. These results disclose the possibility of tuning surface diffusion dynamics and controlling cluster nucleation and self-organization.
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Picone
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Riva
authors.affiliation: ETSF, CNISM, Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, I-20125 Milano, Italy and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, I-20133 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Fratesi
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Brambilla
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bussetti
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Finazzi
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Duò
authors.affiliation: CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Ciccacci