Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 13: Magnetismus

O 13.3: Vortrag

Freitag, 4. März 2005, 16:15–16:30, TU EB107

Spin polarization and electron confinement in nanoscale Co islands on Cu(111) — •Oswald Pietzsch, André Kubetzka, Stefan Heinze, Matthias Bode, and Roland Wiesendanger — Institute of Applied Physics,University of Hamburg,Jungiusstrasse 11, 20355 Hamburg, Germany

Spin-polarized scanning tunneling spectra (SP-STS) of nanoscale ferromagnetic Co islands on Cu(111) show that the spin polarization (SP) is strongly dependent on the energy in the vicinity of the Fermi level [1]. In particular, the sign of SP is reversed several times within the observed energy window. We discuss possible explanations based on first principles spin-resolved band structure calculations.

Similar to the Cu surface, the Co islands exhibit a standing wave pattern in the local density of states (LDOS) which can be observed by STM [2]. A comparison of the Co and Cu patterns as a function of energy reveals the essential difference: while the latter shows two-dimensional (2D) free electron gas behavior, the former is determined by lateral electron confinement. We compare our results with models based on an exact solution of the particle-in-a-triangular-box problem and a multiple scattering approach. signature of the island rim which is yet different from that of both Co and Cu.

[1] O. Pietzsch et al., Phys. Rev. Lett., 92, 057202 (2004).

[2] L. Diekhöner et al., Phys. Rev. Lett. 90, 236801 (2003).