Anomalously large $g$-factor of single atoms adsorbed on a metal substrate

ORAL

Abstract

We performed magnetic field dependent inelastic scanning tunneling spectroscopy (ISTS) on individual Fe atoms adsorbed on different metal surfaces. ISTS reveals a magnetization excitation which is shifting linearly to higher energies in the magnetic field. The data is used to extract the magnetic anisotropies and the $g$-factors of the Fe atoms, as well as the lifetimes of the excitations. We find lifetimes of hundreds of femtoseconds limited by coupling to electron-hole pairs in the substrate and decreasing linearly upon application of the magnetic field. As expected, the magnetic anisotropy strongly depends on the substrate. Astoundingly, we find that the $g$-factor is $g \approx 3.1$ for Ag(111) instead of the regular value of 2 which is observed for the Cu(111) substrate [1]. This very large $g$-shift can be understood when considering the complete electronic structure of both the Ag(111) surface state and the Fe atom, as shown by \textit{ab initio} calculations of the magnetic susceptibility. \\[4pt] [1] A. A. Khajetoorians et al., Phys. Rev. Lett. \textbf{106}, 037205 (2011).

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Authors

  • Jens Wiebe

    • Institute of Applied Physics, Hamburg University, Hamburg, Germany
    • Institute of Applied Physics, Hamburg University, Jungiusstrasse 11, D-20355 Hamburg, Germany

  • Alexander A. Khajetoorians

    • Institute of Applied Physics, Hamburg University, Jungiusstrasse 11, D-20355 Hamburg, Germany

  • Bruno Chilian

    • Institute of Applied Physics, Hamburg University, Jungiusstrasse 11, D-20355 Hamburg, Germany

  • Roland Wiesendanger

    • Institute of Applied Physics, Hamburg University, Jungiusstrasse 11, D-20355 Hamburg, Germany

  • Samir Lounis

    • Forschungszentrum J\"{u}lich, Peter Gr\"unberg Institut and Institute for Advanced Simulation, 52425 J\"{u}lich, Germany

  • Antonio T. Costa

    • Instituto de F\'isica, Universidade Federal Fluminense, 24210-340 Niter\'oi, Rio de Janeiro, Brazil

  • Douglas L. Mills

    • Department of Physics and Astronomy, University of California Irvine, California, 92697 USA