Magnetic Impurities on Superconducting Surfaces: Phase Transitions and the Role of Impurity-Substrate Hybridization

Abstract

Spin-dependent scattering from magnetic impurities inside a superconductor gives rise to Yu-Shiba-Rusinov (YSR) states within the superconducting gap. As such, YSR states have been very successfully modeled with an effective scattering potential (Kondo impurity model). Using a scanning tunneling microscope, we exploit the proximity of the tip to a surface impurity and its influence on the YSR state to make a quantitative connection between the YSR state energy and the impurity-substrate hybridization. We corroborate the coupling between impurity and substrate as a key energy scale for surface derived YSR states using the Anderson impurity model in the mean field approximation, which accurately explains our observations. The model allows to decide on which side of the quantum phase transition the system resides based on additional conductance measurements. We propose that the Anderson impurity model is much more appropriate to describe YSR states from impurities on a superconducting surface than the Kondo impurity model, which is more appropriate for impurities inside a superconductor. We thus provide a first step towards a more quantitative comparison of experimental data with fully correlated calculations based on the Anderson impurity model.

arXiv comment12 pages, 7 figures, including supplementary material

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Cited by in corpus (9)

• Yu-Shiba-Rusinov states in real metals
• Observation of tunable single-atom Yu-Shiba-Rusinov states
• Long range and highly tunable interaction between local spins coupled to a superconducting condensate
• Spatially dispersing Yu-Shiba-Rusinov states in the unconventional superconductor ${\mathrm{FeTe}}_{0.55}{\mathrm{Se}}_{0.45}$
• Tunneling processes between Yu-Shiba-Rusinov bound states
• Boosting the STM's spatial and energy resolution with double-functionalized probe tips
• Effect of Van Hove singularities on Shiba states in two-dimensional $s$-wave superconductors
• Microwave Excitation of Atomic Scale Superconducting Bound States
• Study of Yu-Shiba-Rusinov bound states by tuning the electron density at the Fermi energy