Dresden 2003 – wissenschaftliches Programm

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SYMN: Metallic nanowires

SYMN 1: Metallic nanowires I

SYMN 1.4: Hauptvortrag

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

The electron theory of magnetism in monatomic wires — •Matej Komelj — Jošef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia

The probably most essential feature of magnetism in low-dimensional systems is the overwhelming importance of orbital magnetism. Implications for the magnetic properties of such systems are discussed. Magnetic properties of linear chains of atoms are studied by calculating the electronic structure within the framework of the density functional theory and local-spin-density approximation. The influence of the reduced dimensionality is investigated systematically by performing the calculations on bulk, monolayers and monatomic nanowires of transition metals. The experimentally observed trend towards an enhancement of the orbital magnetic moments due to the lowering of the dimensionality can be reproduced, but to do this one has to take into account the orbital dependence of the exchange-correlation potential. In particular, the x-ray-magnetic-circular-dichroism experiments are interpreted by testing the validity of the sum rules which relate the absorption spectra to the spin and angular magnetic moments. A careful consideration is given to the magnetic dipole term which appears in the expression for the spin sum rule but cannot be measured directly without assuming that the spin-orbit coupling is only a weak effect. It is shown, however, that this assumption is strongly violated for one-dimensional wires. Hence, the application of the corresponding sum rule might be reliable only for the systems where the magnitude of the magnetic dipole term is reasonably small.