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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 8.7: Talk
Monday, March 7, 2016, 12:00–12:15, H21
Magnetic anisotropy in Shiba bound states across a quantum phase transition — •Nino Hatter1, Benjamin W. Heinrich1, Michael Ruby1, José I. Pascual2, and Katharina J. Franke1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2CIC nanoGUNE and Ikerbasque, Basque Foundation for Science, Tolosa Hiribidea 78, Donostia-San Sebastian 20018, Spain
Magnetic adsorbates on a superconductor create a scattering potential for the quasi-particles of the superconductor. This leads to so-called Yu-Shiba-Rusinov (Shiba) states inside the superconducting gap and a Kondo resonance outside the gap.
We performed scanning tunneling microscopy and spectroscopy on paramagnetic manganese phthalocyanine molecules adsorbed on the type-I superconductor Pb. At 1.2 K we resolve triplets of Shiba resonances. A multitude of different adsorption sites provides access to a large range of magnetic coupling strengths with the substrate, which we use to identify the origin of the multiplets. We resolve the splitting of the Shiba states throughout the quantum phase transition from the "Kondo screened" to the "free spin" ground state and can link the splitting to the presence of magnetic anisotropy in the molecule-substrate system. Furthermore, the change in intensities of the Shiba resonances allows the unambiguous determination of the many-body ground and excited states.