Resistive transition in disordered superconductors with varying intergrain coupling

Abstract

The effect of disorder is investigated in granular superconductive materials with strong and weak links. The transition is controlled by the interplay of the \emph{tunneling} $g$ and \emph{intragrain} $g_{intr}$ conductances, which depend on the strength of the intergrain coupling. For $g\ll g_{intr}$, the transition involves first the grain boundary, while for $g\sim g_{intr}$ the transition occurs into the whole grain. The different intergrain coupling is considered by modelling the superconducting material as a disordered network of Josephson junctions. Numerical simulations show that on increasing the disorder, the resistive transition occurs for lower temperatures and the curve broadens. These features are enhanced in disordered superconductors with strong links. The different behaviour is further checked by estimating the average network resistance for weak and strong links in the framework of the effective medium approximation theory. These results may be relevant to shed light on long standing puzzles as: (i) enhancement of the superconducting transition temperature of many metals in the granular states; (ii) suppression of superconductivity in homogeneously disordered films compared to standard granular systems close to the metal-insulator transition; (iii) enhanced degradation of superconductivity by doping and impurities in strongly linked materials, such as magnesium diboride, compared to weakly-linked superconductors, such as cuprates.

References in corpus (29)

• Continuous Quantum Phase Transitions
• Strongly linked current flow in polycrystalline forms of the new superconductor MgB2
• Granular Electronic Systems
• Quantum Phase Transitions and Vortex Dynamics in Superconducting Networks
• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Effect of magnetic and non-magnetic impurities on highly anisotropic superconductivity
• Superconductivity-Related Insulating Behavior
• Nanoscale-SiC doping for enhancing Jc and Hc2 in the Superconducting MgB2
• Lifting of nodes by disorder in extended-$s$ state superconductors: application to ferropnictides
• Phase dynamics of inductively coupled intrinsic Josephson junctions and terahertz electromagnetic radiation
• Observation of the Crossover from Two-Gap to Single-Gap Superconductivity through Specific Heat Measurements in Neutron Irradiated MgB2
• Direct observation of nm-scale Mg- and B-oxide phases at grain boundaries in MgB2
• Transport - and inductive critical current densities in superconducting MgB2
• Disorder and transport in cuprates: weak localization and magnetic contributions
• Percolation model for the superconductor-insulator transition in granular films
• Superconducting quantum phase transitions tuned by magnetic impurity and magnetic field in ultrathin a-Pb films
• Island formation in disordered superconducting thin films at finite magnetic fields
• Appearance of ferroelectricity in thin films of incipient ferroelectric
• Resistively shunted Josephson junctions: QFT predictions versus MC results
• Insensitivity of superconductivity to disorder in the cuprates
• Resistive transition in granular disordered high-T${}_c$ superconductors: a numerical study
• Phase transition in site-diluted Josephson junction arrays: A numerical study
• Experimental Study of Positionally Disordered Josephson Junctions Arrays
• d-wave to s-wave to normal metal transitions in disordered superconductors
• Superconducting to normal state phase boundary in arrays of ultrasmall Josephson junctions
• Array of Josephson junctions with a non-sinusoidal current-phase relation as a model of the resistive transition of unconventional superconductors
• Noise in resistively shunted Josephson junctions
• Effects of disorder on lattice Ginzburg-Landau model of d-wave superconductors and superfluids
• Carbon substitution effect in MgB${}_2$

Cited by in corpus (4)

• Substrate mediated nitridation of niobium into superconducting Nb2N thin films for phase slip study
• Array of Josephson junctions with a non-sinusoidal current-phase relation as a model of the resistive transition of unconventional superconductors
• Superconducting-insulator transition in disordered Josephson junctions networks
• From weak to strong-coupling superconductivity tuned by substrate in TiN films