Regensburg 2019 – wissenschaftliches Programm
MA 45.7: Vortrag
Donnerstag, 4. April 2019, 12:15–12:30, H15
Interplay between Yu-Shiba-Rusinov states and spin-flip excitations on magnetic impurities on superconducting NbSe2 substrate — •Shawulienu Kezilebieke1, Rok Žitko2, Marc Dvorak1, Teemu Ojanen3, and Peter Liljeroth1 — 1Department of Applied Physics, Aalto University School of Science, 00076 Aalto, Finland — 2Jožef Stefan Institute, Jamova 39, SI-1001 Ljubljana, Slovenia — 3Laboratory of Physics, Tampere University of Technology, Tampere FI-33101, Finland
Exchange coupling between a magnetic impurity and a superconducting substrate results in the formation of Yu-Shiba-Rusinov (YSR) bound states, which have been recently used in artificial designer structures to realize exotic quasiparticles known as Majorana fermions. At strong coupling, the energies of YSR states are deep in the superconducting gap. At weak coupling, the YSR states migrate towards the superconducting gap edge. Additional spectral features can appear in the presence of magnetic anisotropy with spin S 1, in particular spin-flip excitations outside the superconducting gap. Despite extensive experiments on magnetic impurities that exhibit separately either spin-flip excitations or YSR states, these phenomena have not been observed simultaneously. Here, we investigate the spectral evolution in different metal phthalocyanine molecules on NbSe2 surface as a function of the coupling with the substrate. Using scanning tunneling microscopy (STM), we tune the exchange coupling strength and for manganese phthalocyanine (MnPc) we demonstrate a smooth spectral crossover from the YSR states to intrinsic quantum spin states.