Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 12: Spindependent Transport I
MA 12.10: Vortrag
Dienstag, 27. März 2007, 12:30–12:45, H22
On the asymmetry of the inelastic tunneling spectra on magnetic materials — •Albert F. Takács1, Timofey Balashov1,2, Wulf Wulfhekel1,2, Jürgen Kirschner2, Markus Däne3, Arthur Ernst2, and Patrick Bruno2 — 1Physikalisches Institut, Universität Kalrsuhe (TH), Wolfgang-Gaede Str. 1, 76131 Karlsruhe — 2MPI für Mikrostrukturphysik, Weinberg 2, 06108 Halle — 3Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, 06099 Halle
Inelastic tunneling spectroscopy (ITS) is a valuable tool to study excitations in metallic systems. We have applied ITS to investigate low lying magnetic excitations. For tunneling between a non-magnetic tip and a ferromagnet, the excitations were found to be asymmetric with respect to the Fermi energy.
For Fe(001) magnon creation was found predominantly for tunneling into the ferromagnet, while for opposite bias the excitation is much weaker. For fcc Co(001) strong magnon excitations were found for both positive and negative bias. Using ab-initio calculations of the spin-polarised DOS of the ferromagnets we show that this asymmetry is related to the spin-polarisation of the ferromagnet. This effect has strong implications for the efficiency of the spin transfer effect used in switching of MRAM cells.