Search

Almost constant voltage plateaus on the V(I) curves of long quasi-one-dimensional superconducting aluminum wires placed in magnetic field at temperatures T slightly below the critical superconducting temperature Tc were found which were unexpected for the sample geometry and parameters of the experiment. The plateaus are assumed to be subharmonics of a superconducting gap and arise due to the multiple Andreev reflection and strong quasiparticle overheating in the wire nonequilibrium region. The plateaus are evidence of coexistence of superconductivity and dissipation in such wires. The results presented in the paper could not be described by existing theories., Comment: 7 pages, 4 figures; the author's translation of the original Russian text: V.I. Kuznetsov, A.A. Firsov, Pis'ma v Zhurnal Eksperimental'noi i Teoreticheskoi Fiziki 104, 721 (2016)

It was experimentally found that quantum magnetoresistive hc/2e periodic oscillations of the Little-Parks type in a superconducting mesoscopic ring with decreasing temperature and increasing applied dc current are modified to the sum of harmonic (hc/2e)/m periodic oscillations. Multiple Andreev reflection can be a possible cause of this effect., Comment: 8 pages, 8 figures; the author's translation of the original Russian text: V.I. Kuznetsov, O.V. Trofimov, Pis'ma v Zhurnal Eksperimental'noi i Teoreticheskoi Fiziki 110, 47 (2019)

We measured both quantum oscillations of a rectified time-averaged direct voltage V_{rec}(B) and a dc voltage V_{dc}(B) as a function of normal magnetic field B, in a thin-film aluminum structure of two asymmetric circular loops in series at temperatures below the superconducting critical temperature T_{c}. The V_{rec}(B) and V_{dc}(B) voltages were observed in the structure biased only with an alternating current (without a dc component) and only with a direct current (without an ac component), respectively. The aim of the measurements was to find whether interaction (nonlinear coupling) exists between quantum magnetic-resistive states of two loops at a large distance from each other. The distance between the loop centers was by an order of magnitude longer than the Ginzburg-Landau coherence length \xi(T). At such distance, one would not expect to detect any interaction between the quantum states of the loops. But we did find such an interaction. Moreover, we found that V_{dc}(B) functions (like V_{rec}(B) ones) can be used to describe the quantum states of the loops., Comment: 8 pages, 3 figures, published version

A dc voltage changed periodically with magnetic field is observed on segments of asymmetric aluminum loop without any external dc current at temperatures corresponded to superconducting transition. According to this experimental result a segment of the loop is a dc power source. A possibility of a persistent voltage on segments of an inhomogeneous normal metal mesoscopic loop follows from this result., Comment: 3 pages, 2 figures

The interaction between the quantum states of two aluminum superconducting rings forming an 8-shape circular-asymmetric microstructure was examined under a threading magnetic flux and bias by an alternating current without a dc component. Quantum oscillations of the rectified dc voltage Vdc(B) as a function of magnetic field were measured in the 8-shape microstructure at various bias ac currents and temperatures close to critical. Fourier and wavelet analyses of Vdc(B) functions revealed the presence of various combination frequencies in addition to two ring fundamental frequencies, which suggests the interaction in the structure. Deviation of the Vdc(B) function from oddness with respect to the magnetic field direction was found for the first time., Comment: author english version, 3 pages, 3 figires, Proc. of the XXXIV Conference on Low-Temperature Physics "NT-34" (Russia, 2006)

Periodic quantum oscillations of a rectified dc voltage Vdc(B) vs the perpendicular magnetic field B were measured near the critical temperature Tc in a single superconducting aluminum almost symmetric ring (without specially created circular asymmetry) biased by alternating current with a zero dc component. With varying bias current and temperature, these Vdc(B) oscillations behave like the Vdc(B) oscillations observed in a circular-asymmetric ring but are of smaller amplitude. The Fourier spectra of the Vdc(B) functions exhibit a fundamental frequency, corresponding to the ring area, and its higher harmonics. Unexpectedly, satellite frequencies depending on the structure geometry and external parameters were found next to the fundamental frequency and around its higher harmonics., Comment: author english version, 2 pages, 3 figires, Proc. of the XXXIV Conference on Low-Temperature Physics "NT-34" (Russia, 2006)

We have measured periodic oscillations of rectified dc voltage versus magnetic field V_{dc}(B) in a superconducting aluminum thin-film circular-asymmetric figure-of-eight microstructure threaded by a magnetic flux and biased with a sinusoidal alternating current (without a dc component) near the critical temperature. The Fourier spectra of these V_{dc}(B) functions contain fundamental frequencies representing periodic responses of the larger and smaller asymmetric circular loops, composing the microstructure, to the magnetic field. The higher harmonics of the obtained fundamental frequencies result from the non-sinusoidal character of loop circulating currents. The presence of the difference and summation frequencies in these spectra points to the interaction between the quantum states of both loops. Magnitudes of the loop responses to the bias ac and magnetic field vary with temperature and the bias current amplitude, both in absolute values and with respect to each other. The strongest loop response appears when the average resistive state of the loop corresponds to the midpoint of the superconducting-normal phase transition., Comment: 5 pages; 2 figures; minor changes in grammar; shortened title

We have found that the thin film aluminum structures shaped into a chain of micron sized islands connected by narrow isthmuses, can modify their electrical and structural properties under microwave radiation. As a result, at the temperature of 4.2 K the film structures turn into a kind of lateral periodic structure N-S-N, where N is for normal islands, S is for superconducting isthmuses. Current-voltage characteristics of the samples, as well as changes of these characteristics under low power radiation, have been studied over the temperature range from 1.3 to 10 K. The sensitivity of a structure as a microwave detector runs 10^{5} V/W., Comment: 4 pages, 4 figures, RevTex4

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 \Omega/2\pi\=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)U_{\Omega}, where m and n are integers and U_{\Omega} is determined by Josephson's formula \hbar\Omega=2eU_{\Omega}, 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., Comment: 7 pages, 6 figures, RevTex4. Several of the translated words defined more exactly

The appearance of phase-slip lines, induced by an rf field, was observed experimentally in wide superconducting films in which the destruction of superconductivity by a dc current is associated with the formation of phase-slip lines. The characteristics of the separation of the film into superconducting and nonuniform, isothermal, nonequilibrium regions (phase-slip lines) under electromagnetic irradiation were studied., Comment: 4 pages, 3 figures, RevTex4. Misprints of the original paper corrected. Numeric format(separators)in Figures changed

An experimental investigation was made of the temperature dependence of the first step of a phase-slip line in a thin superconducting tin film. The depth of penetration of a nonequilibrium longitudinal electric field into the superconductor was determined near the critical temperature. A comparison was made with theoretical investigations of one-dimensional structures containing phase-slip centers. The experimental results were found to be in good agreement with the theory when the mechanism of mixing of electron-like and hole-like branches of the quasiparticle spectrum was governed by the elastic scattering of the excitations. This was one more experimental confirmation that a phase-slip line is a two-dimensional analog of a phase-slip center., Comment: 3 pages, 2 figures, Revtex4. Numeric format(separators)in Figures changed

A nonmonotonic dependence of the differential resistance of the first step of a phase-slip line on the heat-reservoir temperature near Tc has been observed experimentally for the first time in a superconducting tin film. This behavior is interpreted as a conversion of the phase-slip line into an elementary resistive domain as the result of a deviation from the isothermal conditions., Comment: 3 pages, 3 figures, RevTex4. Present address of the first author added

A vortex-induced transverse voltage in a superconducting film, previously predicted theoretically, has been seen experimentally for the first time. The magnitude of this voltage and its nonmonotonic current dependence are explained on the basis of a curvature of the trajectory of vortices resulting from their interaction. A good agreement between theory and experiment is found., Comment: 2 pages, 2 figures, RevTex4. Misprints of the original paper corrected. Present address of the third author added. PACS numbers corrected

A theoretical prediction published in Phys.Rev. B 64, 012505 (2001) is corroborated experimentally. This corroboration of the theoretical result published in Physical Review B was rejected for publication in the same journal. Such inconsistency is connected with a contradiction to the second law of thermodynamics. According to the theory Phys.Rev. B 64, 012505 (2001) the energy of a noise can be transformed to a dc power in superconducting loop and therefore a dc voltage oscillating with magnetic field can be observed on segments of an inhomogeneous loop in the temperature region close to the superconducting transition. Such quantum voltage oscillations observed in the present work can be induced both by an external electrical noise and by internal equilibrium noise (thermal fluctuations). Violation of the second law takes place in the second case. First of all the theoretical result published by Phys.Rev.B is challenge to the second law but about this contradiction was openly written only in the first version (see physics/0105059) of the experimental paper rejected by Referees of Phys.Rev.B. The transformation of an external electrical noise to the dc voltage was confirmed recently in the paper published in JETP Letters 77, 371 (2003) (see also cond-mat/0303538)., Comment: 4 pages, 5 figures

A dc voltage induced by an external ac current is observed in system of asymmetric mesoscopic superconducting loops. The value and sign of this dc voltage, like the one of the persistent current, depend in a periodical way on a magnetic field with period corresponded to the flux quantum within the loop. The amplitude of the oscillations does not depend on the frequency of the external ac current (in the investigated region 100 Hz - 1 MHz) and depends on its amplitude. The latter dependence is not monotonous. The observed phenomenon of rectification is interpreted as a consequence of a dynamic resistive state induced by superposition of the external current and the persistent current. It is shown that the dc voltage can be added in system of loops connected in series: the dc voltage oscillations with amplitude up to 0.00001 V were observed in single loop, up to 0.00004 V in a system of 3 loops and up to 0.0003 V in a system of 20 loops., Comment: 5 pages, 6 figures

In order to verify a possibility of a dc voltage predicted on segments of an inhomogeneous superconducting loop the Little-Parks oscillations are investigated on symmetrical and asymmetric Al loops. The amplitude of the voltage oscillations $\Delta V$ measured on segments of symmetrical loop increases with the measuring current $I_{m}$ and $\Delta V = 0$ at $I_{m}= 0$ in accordance with the classical Little-Parks experiment. Whereas the $\Delta V$ measured on segments of asymmetric loop has a maximum value at $I_{m}= 0$. The observation of the dc voltage at $I_{m}= 0$ means that one of the loop segments is a dc power source and others is a load. The dc power can be induced by both thermal fluctuation and a external electric noise., Comment: 4 pages, 4 figures