Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 22: Surface or Interface Magnetism
O 22.4: Vortrag
Dienstag, 27. März 2007, 12:00–12:15, H36
Magnetic linear dichroism in time-resolved two-photon photoemission — Martin Pickel1, Anke Schmidt2, Andreas Goris2, •Fabian Giesen2, Martin Weinelt2,3, and Markus Donath1 — 1Physikalisches Institut, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster — 2Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin — 3Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin
Magnetic linear dichroism in photoemission spectroscopy, i.e. a magnetization-direction dependence of the intensity, has so far only been observed in direct excitation processes [1].
We will present a two-photon photoemission (2PPE) study on ultrathin cobalt films on Cu(100), where the image-potential states (IPS) show a strong dichroism. Varying the photon energy, however, reveals that its origin is caused by initial-states of the 2PPE process. What is more, a spin-dependent lifetime of the IPS in combination with a magnetization direction dependent spin polarization leads to a "dichroic" lifetime in time-resolved 2PPE. This enables a determination of the initial state quantum number without any spin-resolution. The corresponding direct spin-resolved measurements substantiate this possibility and demonstrate that spin-resolved 2PPE can be used as a probe for the electronic structure of occupied states close to the Fermi-level with respect to the spin polarization and the symmetry quantum number.
[1] W. Kuch and C. M. Schneider, Rep. Prog. Phys. 64, 147 (2001)