Resolving the Yu-Shiba-Rusinov States in Fe Nanostructures on Superconducting Ni-Kagome Monolayer

Nitin Kumar^1*, Raffaele Aliberti², Yen-Hui Lin¹, Philipp Rüßmann², Gustav Bihlmayer², Pin-Jui Hsu^1,3

¹Department of Physics, National Tsing Hua University, Hsinchu 300044, Taiwan
²Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
³Center for Quantum Technology, National Tsing Hua University, Hsinchu 300044, Taiwan

* Presenter:Nitin Kumar, email:itsnitin95@gmail.com

Recently, Yu-Shiba-Rusinov (YSR) states have attracted considerable attention due to the theoretical prediction to support the emergence of Majorana zero modes (MZMs) as a fundamental building block of quantum qubits. In this work, monolayer Ni Kagome islands were synthesized on a bulk superconductor (SC) Pb substrate, and subsequent deposition of Fe atoms resulted in well-defined monomer and trimer impurity nanostructures. High spatial- and energy-resolution STM/STS measurements resolve the one and three pairs of YSR bound states within the SC gap for Fe-monomer and -trimer, respectively. The conductance mapping in the real space displays a very distinctive dispersion of individual YSR states. A comprehensive analysis via Kohn-Sham Bogoliubov-de Gennes (KS-BdG) computational method not just resolved the orbital contribution to the individual YSR states but also explained the distinct spatial distribution on the neighboring Ni and Pb atoms. This study provides deep insight into the exchange interactions between the Fe magnetic impurities and the SC condensates in a structurally complex, non-magnetic Kagome host lattice.

Keywords: Yu-Shiba-Rusinov bound states, atomic-scale magnetism, Kagome Lattice, superconductivity, STM/STS