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AM: Magnetismus

AM 19: Spektroskopie I

AM 19.11: Vortrag

Donnerstag, 30. März 2000, 12:15–12:30, H22

The Electron Analogue to the Faraday Rotation — •S. Riesen, W. Weber, and H.C. Siegmann — Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Schweiz

Since the discovery of the wave-like nature of the electron, it became obvious that it might be of interest to carry out experiments with polarized electrons in analogy to experiments with polarized light. The vector of the electron spin polarization should appear as the analogue of the light polarization vector.

To study this phenomenon, the transmission of polarized electrons across free standing ferromagnetic films is investigated. If the incoming spin polarization vector is chosen perpendicular to the magnetization, the exchange energy should result in a precession of the spin polarization vector around the magnetization.

The precession angle increases linearly with film thickness with a slope of 15 and 20 degrees/nm for Co and Fe, respectively, at electron energies close to the vacuum level. With increasing energy the precession angle decreases steeply, which is due to the fact that the exchange energy is reduced when the energy increases. The observed spin motion is in analogy to the Faraday rotation with light, and opens up the possibility to measure the exchange energy for energies above the vacuum level.