Dresden 2011 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.1: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

Spin-resolved microspectroscopy of Co thin films on Cu(100) using one- and two-photon photoemission — •Martin Ellguth, Christian Tusche, Cheng-Tien Chiang, A. Akin Ünal, Aimo Winkelmann, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

We measure spin-polarized photoelectron emission microscopy images of Co films with a thickness of 8 to 12 monolayers grown on Cu(100), using one- and two-photon (1PPE, 2PPE) photoemission (photon energy = 6.0 eV and 3.1 eV, respectively). Our photoelectron emission microscope (PEEM) is equipped with both a double hemispherical energy analyzer and an imaging spin-detector. Spin filtering of the full PEEM image is achieved by low-energy scattering of the photoelectrons at a W(100) crystal under specular reflection by 90 degrees. Compared to classical spin-resolved electron spectrometers, the two-dimensional detection scheme offers the simultaneous measurement of an entire spatial image and recording of the magnetic domain structure of the Co film at a selected energy.

Final-state energy spectra of the Co films in 1PPE and 2PPE show a positive spin-polarization background arising from the Co electronic structure. We find a superimposed reversal of the spin polarization due to the contribution of the surface resonance state of Co with minority spin character. In comparison, the unoccupied quantum well state of the Co thin film causes enhanced spin polarization in 2PPE, in a thickness-dependent energy range.