Temperature dependent energy gap for Yu-Shiba-Rusinov states at the quantum phase transition

Abstract

Motivated by recent experiments, which allow for fine tuning of the effective magnetic interaction between the impurity and the superconductor, we investigate the regime around the quantum phase transition where the system's ground state changes from a weakly coupled free spin to a screened spin regime. At this transition we find that the Yu-Shiba-Rusinov (YSR) states remain at finite energies at low temperatures, thereby generating a gap in the spectrum, which is inconsistent with predictions of the original YSR theory. We investigate various gap-generating scenarios and determine that the local suppression of the order parameter, only captured by self-consistent calculations, generates the gap.

15 pages, 6 figures

References in corpus (15)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Continuous-time Monte Carlo methods for quantum impurity models
• The Kernel Polynomial Method
• Shiba states and zero-bias anomalies in the hybrid normal-superconductor Anderson model
• Chebyshev-BdG: an efficient numerical approach to inhomogeneous superconductivity
• Self-organized topological state in the magnetic chain on the surface of a superconductor
• Robust poor man's Majorana zero modes using Yu-Shiba-Rusinov states
• Impurities, Quantum Interference and Quantum Phase Transitions in s-wave superconductors
• The Andreev states of a superconducting quantum dot: mean field vs exact numerical results
• Superconducting Quantum Interference at the Atomic Scale
• Interplay Between Yu-Shiba-Rusinov States and Multiple Andreev Reflections
• Universal scaling of tunable Yu-Shiba-Rusinov states across the quantum phase transition
• Effect of Van Hove singularities on Shiba states in two-dimensional $s$-wave superconductors
• Shiba states in systems with density of states singularities
• YSR Bond Qubit in a Double Quantum Dot with cQED Operation