Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 60: Time-Resolved Spectroscopies
O 60.7: Vortrag
Donnerstag, 29. März 2007, 17:15–17:30, H42
Spin-dependent lifetimes of hot electrons in Co/Cu(100) revisited — •Ilja Panzer1,3, Andreas Goris1,3, Martin Pickel2, Anke Schmidt1,3, Fabian Giesen1, Markus Donath2, and Martin Weinelt1,3 — 1Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin — 2Physikalisches Institut, Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster — 3Freie Universität Berlin, Arnimallee 14, 14195 Berlin
There is an ongoing controversy over hot electron lifetimes in ferromagnetic metals from the experimental as well as the theoretical point of view [1,2]. From the various experimental approaches to measure the lifetimes of excited electrons no consistent picture of the underlying processes has emerged. For ferromagnetic thin films it is widely accepted that the lifetime of excited electrons is spin dependent, but the ratio between majority and minority lifetimes is still not settled.
We have measured the spin-dependent lifetimes of hot electrons between 250 and 750 meV above EF for 20 ML Co/Cu (100) with time-resolved two-photon photoemission. Hot electrons are created by a 1.5 eV IR pulse of 3 nJ and probed with a significantly weaker UV pulse with the UV photon energy tuned slightly below the work function thus reducing the background of direct photoemission. We find significantly different lifetimes for minority and majority electrons. The implication for ultrashort magnetic switching will be discussed.
[1] Aeschlimann et al., Phys. Rev. Lett. 79, 5158 (1997)
[2] Zhukov et al., Phys. Rev. Lett. 93, 096401 (2004)