Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.77: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

Surface and Image-Potential States of Gadolinium Investigated with Spin- and Time-Resolved 2PPE — •Beatrice Andres^1,2, Kristian Döbrich¹, Andreas Goris^1,2, Anke B. Schmidt³, Markus Donath³, and Martin Weinelt^1,2 — ¹Max-Born-Institut, 12489 Berlin — ²Fachbereich Physik, Freie Universität Berlin, 14195 Berlin — ³Physikalisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster

It is still an open question which microscopic processes are responsible for the laser-induced ultrafast demagnetization in ferromagnetic materials. Most of the experiments performed so far lack spin-resolution.
Our first goal is to investigate the occupied majority and unoccupied minority 5d_z² surface state (SS) of Gd, following the work of Ref. [1]. We will investigate exchange splitting ΔE_ex, binding energy and spin polaristion of the SS and their dependence on the temperature. Here the fundamental of our Ti:Sa laser serves as IR pump and the frequency tripled UV as probe pulse (photon energies 1.5 and 4.5 eV, respectively, pulse durations ≈ 40 fs).
In a second step we will focus on the image-potential states which are also expected to show ΔE_ex and spin dependent lifetimes (frequency doubled photons at hν=3 eV will serve as pump and 1.5-eV-photons as probe). As samples we use 100-Å-thick Gd(0001) films grown in situ on W(110).

[1] M. Lisowski et. al., Phys. Rev. Lett. 95, 137402 (2005).