Dresden 2003 – wissenschaftliches Programm

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SYMN: Metallic nanowires

SYMN 1: Metallic nanowires I

SYMN 1.3: Hauptvortrag

Freitag, 28. März 2003, 10:30–11:00, HSZ/01

Experimental investigation of magnetism in monatomic wires — •Pietro Gambardella — Institut de Physique des Nanostructures (IPN), EPFL, PHB-Ecublens, CH-1015 Lausanne, Suisse

We report on the first investigation of magnetism in one-dimensional (1D) monatomic chains of metal atoms. Whereas statistical models forbid long-range ferromagnetic order in infinite 1D spin chains at any temperature greater than zero, finite-size systems might escape such restrictions. Due to difficulties in reaching thermodynamic equilibrium, 1D monatomic Co wires constructed on a Pt substrate show evidence for both short- and long-range ferromagnetic order, depending on the substrate temperature. We show that ferromagnetism in 1D is stabilized by unusually strong magnetic anisotropy barriers (2 meV/atom) which in turn arise from the reduced dimensionality of the wires. The magnetic properties, in particular the orbital magnetization and the magnetic anisotropy, change drastically as the systems evolves from a 1D wire to a 2D monolayer.