Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 28: Surface Magnetism
MA 28.2: Vortrag
Donnerstag, 29. März 2007, 15:30–15:45, H23
Spin-Polarised Scanning Tunneling Spectroscopy as a tool to study magnetic excitations — •Timofey Balashov1,2, Albert F. Takács2, Wulf Wulfhekel1,2, and Jürgen Kirschner1 — 1MPI für Mikrostrukturphysik, Weinberg 2, 06108 Halle — 2Physikalisches Institut, Universität Kalrsuhe (TH), Wolfgang-Gaede Str. 1, 76131 Karlsruhe
Electron scattering processes play an important role in modern spin electronics. In magnetic materials electrons can scatter and create magnons. We used inelastic tunneling spectroscopy (ITS) to laterally resolve magnon excitations.
ITS was performed at 4K in ultra-high vacuum on paramagnetic (Cu) and ferromagnetic (Fe, Co) surfaces. While no inelastic peaks were observed on Cu, ferromagnets exibit inelastic peaks on the d2I/dU2 curve in the vicinity of the Fermi energy. We prove that these excitations are of magnetic origin by spin-polarised scanning ITS with ferromagnetic tips. The inelastic peak intensities depend on the relative orientation of tip and sample magnetisations, i.e on the spin of the tunneling electron, indicating that the observed excitations are indeed magnons. We demonstrate that the cross section of magnon creation in these materials is high enough to allow direct observation (≈27% for bulk Fe and ≈2% per monolayer of Co on Cu(111)). Mapping the magnon yield as function of the tip position allows lateral imaging of magnon excitations.