Spin- and time-resolved photoemission studies of thin Co2FeSi Heusler alloy films

We have studied the possibly half metallic Co2FeSi full Heusler alloy by means of spin- and time-resolved photoemission spectroscopy. For excitation, the second and fourth harmonic of femtosecond Ti:sapphire lasers were used, with photon energies of 3.1 eV and 5.9 eV, respectively. We compare the de...

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Bibliographic Details
Published in:arXiv.org 2006-05
Main Authors: J -P Wüstenberg, Cinchetti, M, M Sánchez Albaneda, Bauer, M, Aeschlimann, M
Format: Article
Language:English
Subjects:
Dependence
Electrons
Excitation spectra
Heusler alloys
Photoelectric emission
Photon absorption
Polarization (spin alignment)
Sapphire
Surface layers
Thin films
Titanium
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Summary:We have studied the possibly half metallic Co2FeSi full Heusler alloy by means of spin- and time-resolved photoemission spectroscopy. For excitation, the second and fourth harmonic of femtosecond Ti:sapphire lasers were used, with photon energies of 3.1 eV and 5.9 eV, respectively. We compare the dependence of the measured surface spin polarization on the particular photoemission mechanism, i.e. 1-photon-photoemission (1PPE) or 2-photon photoemission (2PPE). The observed differences in the spin polarization can be explained by a spin-dependent lifetime effect occurring in the 2-photon absorption process. The difference in escape depth of the two methods in this context suggests that the observed reduction of spin polarization (compared to the bulk) cannot be attributed just to the outermost surface layer but takes place at least 4-6 nm away from the surface.
ISSN:2331-8422
DOI:10.48550/arxiv.0606006