Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Surface Magnetism

MA 13.11: Talk

Tuesday, February 26, 2008, 13:00–13:15, EB 301

Quantitative determination of spin-dependent quasiparticle renormalization in ferromagnetic 3d metals — •Jaime Sánchez-barriga, Andrei Varykhalov, Jörg Fink, Oliver Rader, Hermann Dürr, and Wolfgang Eberhardt — Bessy GmbH, Albert Einstein str. 15, D-12489, Berlin, Germany

Spin dependent low-energy electronic excitations in 3d ferromagnets are of special interest due to the need of a microscopic understanding of the electronic structure of solids. Low-energy electrons (or holes) become dressed by a cloud of excitations resulting in quasiparticles of a finite lifetime and a different effective mass. These type of excitations have been studied by many theoretical methods, and it has been found that because of many body effects no sharp quasiparticle peaks exist for binding energies larger than 2 eV. Interestingly, it has been shown that strong correlation effects could particularly affect majority spin electrons, leading to a pronounced damping of quasiparticles at binding energies around 2 eV and above. In order to give an experimental corroboration to these findings, we have performed a systematic study of the spin-dependent quasiparticle lifetime and band structure of ferromagnetic 3d transition metal surfaces by means of spin and angle-resolved photoemission spectroscopy. On hcp Co(0001), fcc Ni(111) and bcc Fe(110), we have found a more pronounced renormalization of the majority spin quasiparticle spectral weight going from Ni to Co which are both strong ferromagnets. For Fe, a weak ferromagnet, such a process becomes more prominent in the minority channel.