Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 39: Nanostructures III
O 39.1: Talk
Thursday, March 30, 2006, 15:00–15:15, PHY C213
Spin-dependent excitation of surface states on ultrathin ferromagnetic films — •Martin Pickel1, Anke B. Schmidt2, Martin Weinelt2, and Markus Donath1 — 1Physikalisches Institut, Universität Münster, Wilhelm-Klemm Str. 10, 48194 Münster — 2Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin
Studying image-potential states with time-resolved two-photon photoemission (2PPE) has provided new insight into electron dynamics at surfaces. Recent spin-resolved measurements of electron dynamics in front of ultrathin iron films [1] even allow for the distinction between majority- and minority-spin electron scattering channels.
In this talk we discuss the initial, pump-induced spin polarization of the image-potential states in front of ultrathin iron and cobalt films on Cu(001). Following the argument of spin-integrated studies for the n=1 image-potential state [2], the spin polarization can be ascribed to the initial bulk states and the dipole selection rules governing the pump process. Additionally, we observe linear dichroic effects with 2PPE.
Therefore, by 2PPE we do not only obtain information about image-potential states itself but also about the initial states. They must have a considerable overlap with the image-potential states which makes this method very surface sensitive.
[1] A. B. Schmidt et al., Phys. Rev. Lett. 95, 107402 (2005)
[2] U. Thomann et al., Appl. Phys. B 68, 531 (1999)