Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 76: Superconductivity: Tunnelling and Josephson Junctions II

TT 76.5: Talk

Thursday, March 21, 2024, 16:00–16:15, H 3010

Analysis of Inelastic Tunneling Spectrum of Lead Phthalocyanine Adsorbed on Superconducting Pb(100) — •Athanasios Koliogiorgos and Richard Korytár — Department of Condensed Matter Physics, Charles University in Prague, Czech Republic

A wealth of information can be gained from the vibrational spectrum of adsorbed molecules on metal surfaces. Such spectrum can be accessed by inelastic electron tunneling in scanning-tunneling microscopy. A recent experimental study has reported resonances in a lead phthalocyanine (PbPc) molecule on a superconducting Pb(100) which were attributed to vibrational excitations. These excitations appear as peaks in the first derivative of the current-voltage relation within the superconducting gap, in a scanning-tunneling setup. Here we introduce an innovative computational approach to analyze the inelastic tunneling spectra of PbPc adsorbed on Pb(100) surfaces. Our method focuses on the vibrational spectrum observed in the first derivative of the current-voltage relation. This spectrum provides insights into the adsorbate’s vibrational transitions and the interplay of electronic and vibrational states in molecular systems. Our approach diverges from conventional methods by calculating vibrational transitions from isolated molecular electronic orbitals, thus avoiding issues related to the continuous density of states in metals. This refinement facilitates an accurate interpretation of the experimental spectra. Our results highlight the importance of considering two-vibron processes. We also explore the impact of charge transfer and molecular magnetism on the vibrational spectrum by comparing neutral and charged states of PbPc.

Keywords: DFT; EV coupling; Spectral function