Strongly disordered pseudogapped superconductors are expected to display arbitrarily high values of kinetic inductance close to the superconductor-insulator transition (SIT), which make them attractive for the implementation of large dissipationless inductance. We develop the theory of the collective modes in these superconductors and discuss associated dissipation at microwave frequencies. We obtain the collective mode spectra dependence on the disorder level and conclude that collective modes become a relevant source of dissipation and noise in the outer proximity of the SIT.
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http://dx.doi.org/10.1103/PhysRevLett.120.037004 | DOI Listing |
Phys Rev E
February 2023
Department of Physics, Institute for Advanced Studies in Basic Sciences, Zanjan 45137-66731, Iran.
The ordinary (superconductor-insulator-superconductor) Josephson junction cannot exhibit chaos in the absence of an external ac drive, whereas in the superconductor-ferromagnet-superconductor Josephson junction, known as the φ_{0} junction, the magnetic layer effectively provides two extra degrees of freedom that can facilitate chaotic dynamics in the resulting four-dimensional autonomous system. In this work, we use the Landau-Lifshitz-Gilbert model for the magnetic moment of the ferromagnetic weak link, while the Josephson junction is described by the resistively capacitively shunted-junction model. We study the chaotic dynamics of the system for parameters surrounding the ferromagnetic resonance region, i.
View Article and Find Full Text PDFNat Commun
November 2021
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France.
Beyond a critical disorder, two-dimensional (2D) superconductors become insulating. In this Superconductor-Insulator Transition (SIT), the nature of the insulator is still controversial. Here, we present an extensive experimental study on insulating NbSi close to the SIT, as well as corresponding numerical simulations of the electrical conductivity.
View Article and Find Full Text PDFSci Rep
August 2021
Terra Quantum AG, St. Gallerstrasse 16A, 9400, Rorschach, Switzerland.
We investigate the low-temperature complex impedance of disordered insulating thin TiN and NbTiN films in the frequency region 400 Hz-1 MHz in close proximity to the superconductor-insulator transition (SIT). The frequency, temperature, and magnetic field dependencies of the real and imaginary parts of the impedance indicate that in full accord with the theoretical predictions and earlier observations, the films acquire self-induced electronic granularity and become effectively random arrays of superconducting granules coupled via Josephson links. Accordingly, the inductive component of the response is due to superconducting droplets, while the capacitive component results from the effective Josephson junctions capacitances.
View Article and Find Full Text PDFBeilstein J Nanotechnol
September 2020
National Research University Higher School of Economics, 101000 Moscow, Russia.
We investigate superconductor-insulator quantum phase transitions in ultrathin capacitively coupled superconducting nanowires with proliferating quantum phase slips. We derive a set of coupled Berezinskii-Kosterlitz-Thouless-like renormalization group equations demonstrating that interaction between quantum phase slips in one of the wires gets modified due to the effect of plasma modes propagating in another wire. As a result, the superconductor-insulator phase transition in each of the wires is controlled not only by its own parameters but also by those of the neighboring wire as well as by mutual capacitance.
View Article and Find Full Text PDFJ Phys Condens Matter
February 2020
The School of Graduate Studies, Rutgers University, NJ 08901, United States of America.
Optical properties of four model systems (Na-, K-, Rb- or Cs-doped quasi-two-dimensional X AlSiO; X = Na, K, Rb, or Cs) used to study the metal-insulator transition (MIT) in a deformable lattice are investigated. The doping evolution of the optical absorption band(s) originating from small bipolarons show strong variations depending on the electron-lattice coupling strength [Formula: see text]. Despite the increasing number density of small (bi)polarons, the Na-system remains a stubborn (bi)polaronic insulator due to strong [Formula: see text], while the other three systems show closing of the respective mobility gaps giving way to conducting phases with differing properties.
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