Quasiparticle Screening near a Bosonic Superconductor-Insulator Transition Revealed by Magnetic Impurity Doping

Abstract

Experiments show that the Cooper pair transport in the insulator phase that forms at thin film superconductor to insulator transitions (SIT) is simply activated. This activated behavior depends on the microscopic factors that drive the localization of the Cooper pairs. To test proposed models, we investigated how a perturbation that weakens Cooper pair binding, magnetic impurity doping, affects the characteristic activation energy, $T_0$. The data show that $T_0$ decreases monotonically with doping in films tuned farther from the SIT and increases and peaks in films that are closer to the SIT critical point. These observations provide strong evidence that the bosonic SIT in thin films is a Mott transition driven by Coulomb interactions that are screened by virtual quasi-particle excitations. This dependence on underlying fermionic degrees of freedom distinguishes these SITs from those in micro-fabricated Josephson Junction Arrays, cold atom systems, and likely in high temperature superconductors with nodes in their quasiparticle density of states.

arXiv comment5 pages, 3 figures

References in corpus (27)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Granular Electronic Systems
• Localization of preformed Cooper-pairs in disordered superconductors
• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Fractal superconductivity near localization threshold
• Superconductivity-Related Insulating Behavior
• Localized Superconductivity in the Quantum-Critical Region of the Disorder-Driven Superconductor-Insulator Transition in TiN Thin Films
• Single and two-particle energy gaps across the disorder-driven superconductor-insulator transition
• Theoretical Studies of Superconductor-Insulator Transitions
• Superconductivity in the insulating phase above the field-tuned superconductor-insulator transition in disordered indium oxide films
• Quantum Metallicity on the High-Field Side of the Superconductor-Insulator Transition
• Destruction of localized electron pairs above the magnetic-field-driven superconductor-insulator transition in amorphous InO films
• Observation of Giant Positive Magnetoresistance in a Cooper Pair Insulator
• Collective transport in the insulating state of Josephson junction arrays
• Universal conductivity in the boson Hubbard model in a magnetic field
• Superinsulator-Superconductor Duality in Two Dimensions
• Theory of Magneto-resistance of Disordered Superconducting Films
• Dynamical Conductivity Across The Disorder-Tuned Superconductor-Insulator Transition
• Cooper pair insulator in amorphous films induced by nanometer-scale thickness variations
• Magnetoresistance of an Anderson insulator of bosons
• Superconducting quantum phase transitions tuned by magnetic impurity and magnetic field in ultrathin a-Pb films
• Hyperactivated resistance in TiN films on the insulating side of the disorder-driven superconductor-insulator transition
• Collapse of the Cooper pair phase coherence length at a superconductor to insulator transition
• Superconductor-Insulator Transition and Fermi-Bose Crossovers
• dc Conductivity of an array of Josephson junctions in the insulating state
• Superconductor-insulator transition of Josephson-junction arrays on a honeycomb lattice in a magnetic field
• Random gauge models of the superconductor-insulator transition in two-dimensional disordered superconductors

Cited by in corpus (2)

• Disorder-induced superconductor to insulator transition and finite phase stiffness in two-dimensional phase-glass models
• Spin-Polarized Tunneling in Critically Disordered Be-Al Bilayers