Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 4: Oberfl
ächenmagnetismus

MA 4.7: Talk

Monday, March 8, 2004, 11:45–12:00, H22

Spin-Polarized Scanning Tunneling Spectroscopy of Co Islands on Cu(111) — •Oswald Pietzsch, Stefan Heinze, André Kubetzka, Matthias Bode, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany

Spin-averaged and spin-polarized scanning tunneling spectroscopy at low temperature was performed on nanometer-scale triangular Co islands grown epitaxially on Cu(111) in the sub-monolayer coverage regime. Two structurally different island types can clearly be distinguished by their spin-averaged electronic structure. Spin-polarized measurements allow a separation of spectral contributions arising from different island stacking or from opposite magnetization states, respectively. We compare these results with ab initio electronic band structure calculations.

In an applied magnetic field both island types are found to be magnetized perpendicular to the surface, with large values of saturation field, remanence, and coercivity. It is found that for one island type the saturation field is significantly higher than for the other.

As was shown in spin-averaged measurements [1], bias-voltage dependent oscillation patterns of the local density of states (LDOS) due to electron confinement can be observed on the Co islands. Here we present spin-polarized data revealing the oscillation amplitude to depend on the spin direction.

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