Eur. Phys. J. Special Topics 227, 2303–2313 (2019)
https://doi.org/10.1140/epjst/e2018-800056-3

Regular Article

Yu-Shiba-Rusinov bound states versus topological edge states in Pb/Si(111)

¹ Institut des Nanosciences de Paris, Université Pierre et Marie Curie (UPMC), CNRS-UMR 7588, 4 place Jussieu, 75252 Paris, France
² Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
³ Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
⁴ Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, P.R. China
⁵ Laboratoire de physique et d’étude des matériaux, LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, 10 rue Vauquelin, 75005 Paris, France

^a e-mail: pascal.simon@u-psud.fr

Received: 14 April 2018
Received in final form: 10 June 2018
Published online: 18 January 2019

Abstract

There is presently a tremendous activity around the field of topological superconductivity and Majorana fermions. Among the many questions raised, it has become increasingly important to establish the topological or non-topological origin of features associated with Majorana fermions such as zero-bias peaks. Here, we compare in-gap features associated either with isolated magnetic impurities or with magnetic clusters strongly coupled to the atomically thin superconductor Pb/Si(111). We study this system by means of scanning tunneling microscopy and spectroscopy (STM/STS). We take advantage of the fact that the Pb/Si(111) monolayer can exist either in a crystal-ordered phase or in an incommensurate disordered phase to compare the observed spectroscopic features in both phases. This allows us to demonstrate that the strongly resolved in-gap states we found around the magnetic clusters in the disordered phase of Pb have a clear topological origin.