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Coexisting Spin, Vibrational, and Orbital Excitations in Conductance Spectra

Arnab Banerjee1,*, Roberto Robles2, Nicolás Lorente2, Richard Berndt1, and Alexander Weismann1,†

  • *Contact author: banerjee@physik.uni-kiel.de
  • †Contact author: weismann@physik.uni-kiel.de
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Phys. Rev. Lett. 137, 116403 – Published 11 September, 2026

DOI: https://doi.org/10.1103/mwl6-8nzl

Abstract

First-principles predictions of excitation energies and cross sections in inelastic tunneling spectroscopy are challenging, making it difficult to assign experimental features to specific excitations. There is, however, a need for a reliable identification of conductance features. We investigated the spin-1/2 molecule cobaltocene on superconducting Pb(110) and employ Yu-Shiba-Rusinov states combined with a superconducting tip to detect a large number of sharp spectral features. From an analysis of the peak heights at both bias voltage polarities along with model calculations and density-functional theory results we identify spin, vibrational, and orbital excitations that coexist within a single conductance spectrum. The peak height asymmetry turns out to be a useful indicator to determine the type of excitation.

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Phys. Rev. Lett. 137, 116403– Published 11 September, 2026
  • Received 12 January 2026
  • Accepted 30 July 2026
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