Synchronization of high-frequency vibrations of slipping phase centers in a tin whisker under microwave radiation

Abstract

Current-voltage characteristics of a system with a variable number of phase-slip centers resulting from phase separation in a tin whisker under external microwave field with a frequency Ω/2π ≃ 35 − 45 GHz have been studied experimentally. Emergence and disappearance of steps with zero slope in a whisker's current-voltage characteristic at U m/n = (m/n)UΩ, where m and n are integers and UΩ is determined by Josephson's formula Ω = 2eUΩ, have been investigated. Microwave field generated by phase-slip centers is nonharmonic, and the system of phase-slip centers permits synchronization of internal oscillations at a microwave frequency by an external field with a frequency which is the n-th harmonic of internal oscillations. The estimated microwave power generated by a whisker is 10 −8 W. Stimulation of superconductivity in a current-carrying whisker has been detected.

Voltage plateaus on V(I) curves of long quasi-one-dimensional superconducting wires (without microwave irradiation)

“…As the current I decreases the plateau usually transforms into a virtually linear section which ends by an abrupt drop to a state close to the superconducting state. We believe that the excess superconducting current and linear sections on the V (I) curves of the studied wires as well as on the V (I) curves of the wires reported in [12] evidently suggest the presence of the phase slip center in the wire central part. The V (I) curves were found independent of the thermocycling: curves 1 and 2 were measured in one cycle, curves 3 and 4 in another cycle ( Fig.…”

“…Constant voltage plateaus (integers with n = 1 and the Shapiro fractional steps) which appear at V = mhf /2ne (e is the elementary charge, n and m are integers, h is the Planck's constant) on the V (I) curves of superconducting structures with a weak link [10,11] and quasi-one-dimensional wires [12] under microwave irradiation at the frequency f are evidence of alternating superconducting current in the region of the phase slip center.…”

Velocimetry of superconducting vortices based on stroboscopic resonances

“…Their further acceleration in increasing current leads to the formation of a phase-slip 11 , a line of suppressed superconductivity across which the phase of the superconducting order parameter changes by 2 π , and along which phase singularities move with high velocity. Those coreless yet moving singularities are often referred to as Josephson vortices (in analogy to those in S-N-S junctions 12 13 14 15 ).…”

AC Josephson properties of phase slip lines in wide tin films

“…The absence of the steps associated with higher harmonics, n > 1, is a common feature of the experiments on the superconducting films [7] and whiskers [8,20]. The authors of these papers have no explanation for this fact.…”

“…Such low values of the superconducting current compared to the dissipative and critical currents have been also suggested in the theoretical PSL model [5]. Estimations of the Josephson irradiation power from the PSL by formulae [20] (I max dc is the maximum magnitude of the current step) and P = I 2 J R d1 give almost the same results: P SnW12 ≈ 10 −10 W for SnW12 and P SnW5 ≈ 10 −9 W for SnW5, in agreement with the Josephson irradiation power from PSC [20] within an order of magnitude.…”