Are pinholes the cause of excess current in superconducting tunnel junctions? A study of Andreev current in highly resistive junctions
arXiv:1009.1248 · doi:10.1103/PhysRevLett.106.097001
Abstract
In highly resistive superconducting tunnel junctions, excess subgap current is usually observed and is often attributed to microscopic "pinholes" in the tunnel barrier. We have studied the subgap current in superconductor-insulator-superconductor (SIS) and superconductor-insulator-normal-metal (SIN) junctions. In Al/AlOx/Al junctions, we observed a decrease of 2 orders of magnitude in the current upon the transition from the SIS to the SIN regime, where it then matched theory. In Al/AlOx/Cu junctions, we also observed generic features of coherent diffusive Andreev transport in a junction with a homogenous barrier. We use the quasiclassical Keldysh-Green function theory to quantify single- and two-particle tunneling and find good agreement over 2 orders of magnitude in transparency. We argue that our observations rule out pinholes as the origin of the excess current.
arXiv comment4 pages, 4 figures
References in corpus (11)
- Quantum state engineering with Josephson-junction devices
- Controlling the spontaneous emission of a superconducting transmon qubit
- Hybrid single-electron transistor as a source of quantized electric current
- Subgap Conductivity of a Superconducting-Normal Tunnel Interface
- Photon assisted tunneling as an origin of the Dynes density of states
- Andreev Current-Induced Dissipation in a Hybrid Superconducting Tunnel Junction
- Subgap current in superconducting tunnel junctions with diffusive electrodes
- Characterization of a fabrication process for the integration of superconducting qubits and RSFQ circuits
- Mesoscopic proximity effect in double barrier Superconductor/Normal Metal junctions
- Nonlinear shot noise in mesoscopic diffusive normal-superconducting systems
- Subgap conductivity in SIN-junctions of high barrier transparency
Cited by in corpus (27)
- Single-electron current sources: towards a refined definition of ampere
- Vanishing quasiparticle density in a hybrid Al/Cu/Al single-electron transistor
- Electron pairing in the pseudogap state revealed by shot noise in copper-oxide junctions
- Observation of Josephson Harmonics in Tunnel Junctions
- Real-time observation of discrete Andreev tunneling events
- Tunnel-Junction Thermometry Down to Millikelvin Temperatures
- Fragility of multi-junction flux qubits against quasiparticle tunneling
- Experimental realization of a Coulomb blockade refrigerator
- Superconducting tantalum nitride-based normal metal-insulator-superconductor tunnel junctions
- Universality of transport properties of ultra-thin oxide films
- Structural details of Al/Al2O3 junctions and their role in formation of electron tunnel barriers
- Spectroscopy of using Energy-Tunable Defect-Embedded Quantum Dots
- Andreev tunneling in charge pumping with SINIS turnstiles
- Sub-micron normal-metal/insulator/superconductor tunnel junction thermometer and cooler using Nb
- Leakage Current of a Superconductor-Normal Metal Tunnel Junction Connected to a High-Temperature Environment
- Etching suspended superconducting hybrid junctions from a multilayer
- Manifestly non-Gaussian fluctuations in superconductor-normal metal tunnel nanostructures
- Superconducting tunneling spectroscopy of spin-orbit coupling and orbital depairing in Nb:SrTiO
- Local and non-local two-electron tunneling processes in a Cooper pair splitter
- Laterally proximized aluminum tunnel junctions
- The influence of pinholes and weak-points in aluminium-oxide Josephson junctions
- Superconductor-ferromagnet tunnel junction thermoelectric bolometer and calorimeter with a SQUID readout
- Theory of temperature fluctuation statistics in superconductor-normal metal tunnel structures
- Material matters in superconducting qubits
- Highly tunable NbTiN Josephson junctions fabricated with focused helium ion beam
- Nonequilibrium and relaxation effects in tunnel superconducting junctions
- Hard superconducting gap and vortex-state spectroscopy in NbSe van der Waals tunnel junctions