Münster 1999 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

AM: Magnetismus

AM 9: Spektroskopie II

AM 9.2: Vortrag

Dienstag, 23. März 1999, 14:45–15:00, F4

Spin-dependent transmission of electrons across ferromagnets — •Stefan Riesen, Wolfgang Weber, Daniel Oberli, and Hans-Christoph Siegmann — Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Schweiz

Electrons striking a metal are subject to electron-electron scattering, which is spin-dependent in the case of a ferromagnetic metal. The origin of the scattering asymmetry is the imbalance between majority- and minority-spin electrons in a ferromagnet. Minority holes are more abundant than majority holes, and therefore majority-spin electrons are less scattered than minority-spin electrons. This results in a longer mean free path for majority-spin electrons as compared to minority-spin electrons.

In this work experiments are presented in which the transmission of spin-polarized electrons through ferromagnetic foils is investigated. By measuring the transmitted current for both spin polarization parallel and antiparallel to the sample magnetization, the transmission asymmetry of elastic electrons is determined. Nonvanishing values of the asymmetry are found within the energy range of 5 - 16 eV above the Fermi level, where an elastic signal is still detectable. For the largest foil thicknesses investigated an asymmetry of almost 80 % is observed. By measuring the elastic asymmetry we are able to determine the spin-dependent cross section of the electron-electron scattering.