Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Surface Magnetism I
MA 4.9: Vortrag
Montag, 23. März 2009, 13:00–13:15, HSZ 403
Magnetic Anisotropy of small metal clusters on Pt(111) — •Stefan Gerstl1, Tobias Schuh1, Timofey Balashov1, Albert F. Takács1, Sergey Ostanin2, Arthur Ernst2, Jürgen Henk2, Toshio Miyamachi1, Shigemasa Suga3, Ingrid Mertig2,4, Patrick Bruno2, and Wulf Wulfhekel1 — 1Physikalisches Institut, Universität Karlsruhe (TH), Germany — 2Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany — 3Graduate School of Engineering Science, Osaka University, Japan — 4Institut für Physik, Martin-Luther-Universität Halle, Germany
The key for higher storage density is the magnetic anisotropy energy (MAE), as it is related to the stability of bits in magnetic storage devices. Giant MAE was found for Co clusters on Pt(111) using X-ray magnetic circular dichroism (XMCD) [1]. We show a new approach to obtain the MAE of individual clusters using inelastic scanning tunneling spectroscopy. Single Fe or Co atoms were deposited on Pt(111) at 4 K and assembled by atomic manipulation to form clusters of up to three atoms. The magnetic excitation energy that we determined corresponds to a spin-flip process and is proportional to the MAE. The excitation energies were recorded on a large number of atoms and clusters and averaged. The obtained values of the MAE are 6.5, 5.2 and 5.5 meV/atom for Fe atoms, dimers and trimers respectively, and 10.2, 5.5 and 5.0 meV/atom for Co atoms and clusters. For Co this corresponds well to the MAE values obtained with XMCD [1]. Relativistic ab-initio calculations of fully relaxed structures confirm our results.
[1] P. Gambardella et al., Science 300, 1130 (2003).