Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 112: Electronic structure: Surface magnetism and spin phenomena II
O 112.2: Vortrag
Freitag, 16. März 2018, 10:45–11:00, MA 042
Mechanically-tunable Kondo resonance in a single molecule subjected to the magnetic field reveals pitfalls in determination of the Kondo scale — •Martin Švec1, Martin Žonda2, Oleksandr Stetsovych1, Richard Korytár2, Markus Ternes3, Tomáš Novotný2, and Pavel Jelínek1 — 1Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic — 2Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic — 3Max-Planck-Institut fur Festkorperforschung, Stuttgart, Germany
We study both experimentally and theoretically the mechanically-tunable Kondo resonance using the low-temperature scanning tunneling microscope (STM) to control the coupling of an organic molecule to its underlying metallic substrate. Pulling the molecule with a half-filled orbital and spin 1/2 from the metal surface changes the molecule's magnetic properties from the highly-correlated Kondo-singlet state to the weakly-coupled spin-flip regime, where an externally applied magnetic field can lift the state degeneracy. We employ simulations using the numerical renormalization group (NRG) theory for a reliable quantitative description of the measured low-bias differential conductance spectra and extraction of the characteristic Kondo energy scale spanning about 15 orders of magnitude. We show that the commonly used Fermi-liquid-based (Frota) and perturbative (Appelbaum) fitting procedures can be rather safely used in their corresponding limits of the high correlations and weak coupling, respectively, but they can dramatically fail even without warning signs in the crossover regime.