Resonant modes in Nb baselayer interferometers with two Josephson junctions

Abstract

Resonances in the current-voltage characteristics of interferometers with two Nb-NbOx-Pb window junctions have been experimentally investigated. The data are compared with the theoretical curves computed both for the voltage and for the magnetic field dependence of the resonance amplitudes. Very good agreement is found in all the range of values of the damping parameter Γ=I0 R/Vr, where Vr is the resonant voltage and I0 and R are the maximum Josephson current and the parallel resistance of each junction. New features that cannot be explained in terms of the existing theory have been observed in devices with larger values of the parameter β=2πLI0/Φ0, where L is the loop inductance, and Φ0 is the flux quantum.

d-Wave Induced Zero-Field Resonances in dcπ-Superconducting Quantum Interference Devices

“…(2) by eliminating the parameter d. No fitting parameter has been used. It is noted that for the p SQUIDs only a single resonance is observed, in accordance with the theory [15], which predicts that for G , 2 only the resonance n 1 has to be visible; G p1 ͑4.2 K͒ 1.1, G p2 ͑67 K͒ 0.7. The resonance voltage increases as a function of temperature from 100 mV at 4.2 K to 180 mV at 67 K. This shift is attributed to the temperature dependence of L, and that of the dielectric constant of the SrTiO 3 substrate [23].…”

“…In practice, one deals with a two-dimensional system, so that l equals half the ratio of the effective junction area to the effective SQUID area. Further, the voltage dependence of the current enhancement I nr ͑V ͞V r ͒ in the p SQUID's I͑V ͒ characteristics is given in the parametric form [11,13,15]:…”

Anodization-free fabrication process for high-quality cross-type Josephson tunnel junctions based on a Nb/Al-AlO x /Nb trilayer

“…was determined by fitting the expected shape of the resonance curve to the actual data [47]. The value of the damping parameter Γ = I c R/V res required for performing this fit was extracted from its relation to the current ratio I res /2I c [48]. For the resonance curve shown in figure 11, Γ = 13.3.…”

Magnetic field dependencies of the critical current and of the resonant modes of dc SQUIDs fabricated from superconductors withs +idx2—y2 order-parameter symmetries

“…For the SQUIDs however, the modulation of the Josephson current is the result of macroscopic resonances between the SQUID inductance and the junction capacitances. The problem has been considered theoretically [41Ð44] and experimentally [45] (for a more complete list of references see [46]). In this case, there is only one resonance for symmetric dc SQUIDs which occurs at a frequency w r LCa2 À1a2 , where C is the junction capacitance.…”