Dynamic Impedance of Two-Dimensional Superconducting Films Near the Superconducting Transition

Abstract

The sheet impedances, Z(w,T), of several superconducting a-Mo77Ge23 films and one In/InOx film have been measured in zero field using a two-coil mutual inductance technique at frequencies from 100 Hz to 100 kHz. Z(w,T) is found to have three contributions: the inductive superfluid, renormalized by nonvortex phase fluctuations; conventional vortex-antivortex pairs, whose contribution turns on very rapidly just below the usual Kosterlitz-Thouless-Berezinskii unbinding temperature; and an anomalous contribution. The latter is predominantly resistive, persists well below the KTB temperature, and is weakly dependent on frequency down to remarkably low frequencies, at least 100 Hz. It increases with T as e-U'(T)/kT, where the activation energy, U'(T), is about half the energy to create a vortex-antivortex pair, indicating that the frequency dependence is that of individual excitations, rather than critical behavior.

10 pages, 10 figs; subm PRB

References in corpus (3)

• Dynamic scaling for 2D superconductors, Josephson junction arrays and superfluids
• Effect of thermal phase fluctuations on the superfluid density of two-dimensional superconducting films
• Effect of Thermal Phase Fluctuations on the Inductances of Josephson Junctions, Arrays of Junctions, and Superconducting Films

Cited by in corpus (9)

• Penetration depth and tunneling studies in very thin epitaxial NbN films
• Correlation between superfluid density and Tc of underdoped YBa2Cu3O6+x near the superconductor-insulator transition
• Universal scaling of the critical temperature for thin films near the superconducting-to-insulating transition
• The unusual thickness dependence of superconductivity in $\alpha$-MoGe thin films
• Vortex Fluctuations in the Critical Casimir Effect of Superfluid and Superconducting Films
• Slowing down of vortex motion in thin NbN films near the superconductor-insulator transition
• Suppression of the Berezinskii-Kosterlitz-Thouless and Quantum Phase Transitions in 2D Superconductors by Finite Size Effects
• Anisotropic Kosterlitz-Thouless Transition Induced by Hard-Wall Boundaries
• Effect of Disorder on the Superfluid Transition in Two-Dimensional Systems