Properties of long Josephson junctions, fabricated from YBCO high-temperature superconducting thin films, are investigated experimentally and by numerical modeling. Since the junctions are placed into broadband log-periodic antennas, it poses limitations on junction's bias feed properties, affecting their dynamics. It is shown that biasing junction at the output end, connected to the antenna, makes current-voltage characteristics more steep in comparison with biasing along the whole length and at the input end. The radiation properties of Josephson junctions are studied by receiving signals using dipole antenna array with cold electron bolometers. Broadband frequency tuning of the oscillator with radiation up to 800 GHz, being restricted by the receiver antenna range, is demonstrated. It is shown that for the considered junction lengths and bias feed types, the maximal radiation power varies weakly, leading to a high bolometric response.

A metamaterial receiver, featuring a 19-ring facet structure and intended for usage with a lens, has been successfully designed, fabricated, and tested. The presented concept uses cold-electron bolometers (CEBs) as sensing elements, which enables the design of multiabsorber receivers maintaining a balance between power load and noise. The micrometric size of the CEBs eliminates the need for microwave feed lines, facilitating integration within antenna slots. Using a YBa2Cu3O7-x (YBCO) Josephson junction oscillator, it is demonstrated that the CEB metamaterial receiver has broadband response, approaching 400 GHz, in two frequency bands: 0.15-0.55 and 0.9-1.3 THz. Additionally, the photon-noise-limited operation of the CEB metamaterial, operating at 0.3 K, is shown.

Magnetotransport measurements have been carried out for pristine and irradiated Y Ba2Cu3O7−x films. The measurements reveal a crossover from the clean superconducting limit to the dirty one with an increase in the impurity scattering rate Γ produced by a certain dose of irradiation. For the clean limit, the critical temperature Tc0 decreases with Γ, while the initial slope K=|dHc2/dT|Tc0 increases. We find a nice agreement between these experimental data and a model of d-wave superconductors with anisotropic impurity scattering. Such dose-dependencies of Tc0 and K reveal the superconducting coherence length ξ0 to be quasi-invariant in the clean limit. For the dirty limit, ξ0 increases with Γ due to a decrease in both the quantities Tc0 and K. Though, this decrease appears slower than predicted by the textbook picture of d-wave superconductors. Such discrepancy can be produced by an irradiation-induced modulated disorder responsible for the formation of (d+s)-wave pairing.

We consider properties of dichroic antenna arrays on a silicon substrate with integrated cold-electron bolometers to detect radiation at frequencies of 210 and 240 GHz. This frequency range is widely used in cosmic microwave background experiments in space, balloon, and ground-based missions such as BICEP Array, LSPE, LiteBIRD, QUBIC, Simons Observatory, and AliCPT. As a direct radiation detector, we use cold-electron bolometers, which have high sensitivity and a wide operating frequency range, as well as immunity to spurious cosmic rays. Their other advantages are the compact size of the order of a few micrometers and the effect of direct electron cooling, which can improve sensitivity in typical closed-loop cycle 3He cryostats for space applications. We study a novel concept of cold-electron bolometers with two SIN tunnel junctions and one SN contact. The amplitude–frequency characteristics measured with YBCO Josephson Junction oscillators show narrow peaks at 205 GHz for the 210 GHz array and at 225 GHz for the 240 GHz array; the separation of these two frequency bands is clearly visible. The noise equivalent power level at an operating point in the current bias mode is 5 × 10−16 W/√Hz.

We performed spectral measurements of a large niobium Josephson junctions array. The array consists of 9996 serially connected Nb/NbSi/Nb junctions placed on a 1×1 cm silicon substrate. The spectrum was analyzed by a heterodyne superconducting receiver based on a high-Tc Josephson mixer. It was discovered that the linewidth of Josephson radiation is strongly influenced by configuration and type of a measurement system. We obtain the linewidth down to 0.2 MHz when connecting the array to an autonomous power source and minimizing technical noise. We also observed the shift of the spectral frequency from the Josephson one that can be explained by peculiarities of synchronization of such large multi-oscillator systems.

Magnetotransport measurements were carried out for YBa 2 Cu 3 O 7-x (YBCO) thin films in external perpendicular magnetic fields of H. The studies were performed both for the virgin samples and for the irradiated ones. Xenon ions were used as an external irradiation. Thus we studied features of the broadening of superconducting transition in YBCO films (virgin and irradiated). The broadening of superconducting drop was analyzed depending on an external magnetic field H, as well as on an irradiation dose n D . When processing the experimental data R(H,T), we studied a criterion for determination of temperature dependence of the upper critical field H c2 (T). The criterion was analyzed depending on the defect concentration in the film corresponding to a certain value of n D . It was found out that for a virgin sample, H c2 should be determined by the resistance level R=0.4R N inside the superconducting transition, where R N =R(T=100 K). With a gradual increase in n D , this resistance level decreases. At sufficiently high radiation doses n D >7·10 12 cm -2 , the H c2 (T) phase transition line should be determined by the level R~0. Keywords: thin films, HTSC, xenon ion irradiation, magnetotransport studies, broadening of the superconducting transition, upper critical field, phase transition line, Tinkham's formula, Abrikosov vortices.

Magnetotransport measurements were carried out for YBa_2Cu_3O_{7-x} (YBCO) thin films in external perpendicular magnetic fields of H. The studies were performed both for the virgin samples and for the irradiated ones. Xenon ions were used as an external irradiation. Thus we studied features of the broadening of superconducting transition in YBCO films (virgin and irradiated). The broadening of superconducting drop was analyzed depending on an external magnetic field H, as well as on an irradiation dose n_D. When processing the experimental data R(H, T), we studied a criterion for determination of temperature dependence of the upper critical field H_{c2}(T). The criterion was analyzed depending on the defect concentration in the film corresponding to a certain value of n_D. It was found out that for a virgin sample, H_{c2} should be determined by the resistance level R = 0.4R_N inside the superconducting transition, where R_N = R(T = 100 K). With a gradual increase in n_D, this resistance level decreases. At sufficiently high radiation doses n_D > 7·10^{12} cm^{-2}, the H_{c2}(T) phase transition line should be determined by the level R ≈ 0.

For Josephson bicrystal YBaCuO junctions 3-1.5 $\mu$m in size, the response to an external signal was measured. Receivers with similar $I_{c}R_{N}$ values at helium temperatures and different RN values were considered. The amplitudes of the Shapiro steps were measured for various external signal powers. The dependence of the output voltage noise on structure temperature was measured. It is shown that fluctuations of the critical current have the greatest influence on the output noise of the receiver. The volt-watt sensitivity and noise-equivalent power were evaluated for a 165 GHz external signal. Broadband classical detection of THz radiation by a YBaCuO Josephson junction (JJ) was studied based on resistively and capacitively shunted Josephson Junction model. Optimal temperature operating ranges for the use of each structure were shown.

This work is devoted to the study of epitaxial YBCO films obtained by laser sputtering during deposition of YBCO into the windows of the special preliminary topology mask. The morphology of the surface of the obtained structures was studied by electron microscopy, the electrical characteristics of superconducting bridges were measured: the critical temperature and the critical current density. The possibility of forming YBCO structures of a given topology with defect-free regions of micron sizes while maintaining high electrophysical parameters of the superconductor is shown. This opens up the possibility of reproducibly forming submicron-scale elements in the created defect-free areas using ion etching or ion implantation.

As a follow-up to our study on aggregation of metal-etioporphyrin complexes (Colloids Surf. A. Physicochem. Eng. Asp. 2022, 648, 129284), we considered thin films of three isomers of copper(II) etioporphyrin deposited on hot substrates. Despite the almost identical absorption spectra of isomers, their solid-state superstructures differ remarkably both in form and size. The lateral conductivity of films is much less sensitive to an isomer-type, regardless of the substrate temperature. However, the dark conductivity of cold-grown films is about two orders of magnitude higher than that of hot-grown films, whereas the photoconductivity of the latter is 100–1700 times greater, depending on the isomer.

The resonant properties of Cold-Electron Bolometers (CEBs) located at a 0.3 K cryostat plate are measured using a 50 μm long high-temperature YBa2Cu3O7−δ (YBCO) Josephson junction oscillator, placed on a 2.7 K plate of the same cryostat. For these purposes, a bunch of YBCO Josephson oscillators with various lengths of dipole antennas and overlapping generation bands has been developed and investigated in 50–500 GHz frequency range. Two setups of Josephson junction placement were compared, and as a result, various narrow-band receiving systems with CEBs have been measured, demonstrating the feasibility of the presented approach.

The influence of the contact resistance of the interface of the YBCO/Au structure on the transport and microwave properties of arrays of high-temperature bicrystal Josephson junctions embedded in a coplanar transmission line has been studied. The current-voltage characteristics of Josephson structures fabricated using various technologies are studied: in situ and ex situ with annealing in an oxygen atmosphere. The results obtained can be used to create a quantum ac voltage generator based on high-temperature Josephson junctions. Keywords: high-temperature superconductors, Josephson junctions, microwave, contact resistance.

The disorder effect on superconducting properties of thin-film YBCO nanostructures in external magnetic fields is experimentally studied. The disorder was produced by irradiation with xenon ions. The research included transport measurements of narrow bridges based on HTSC YBCO films (thickness 50 nm) in strong magnetic fields (up to 12 T). Thus, for samples with different degrees of disorder, critical dependencies have been studied, i.e. the Hc2(T) phase transition line, the Hirr(T) irreversibility line, etc. The dependences of the mean-free path and critical temperature on the concentration of defects created by ion irradiation have been experimentally studied. The experimental data are described using formulas obtained within the framework of well-known models, such as the Ginzburg-Landau theory, the Drude theory and the Gorkov equations.

The paper presents the results of a study of the effect of annealing on the critical current of YBCO Josephson junctions obtained by the method of a preliminary topology mask on a bicrystalline substrate. A strong, more than two-fold increase in the critical current of the Josephson junction was detected. This opens up opportunities for managing the current-voltage characteristic of Josephson junctions. Keywords: Josephson junctions, annealing, YBCO.

The influence of the contact resistance of the interface of the YBCO/Au structure on the transport and microwave properties of arrays of high-temperature bicrystal Josephson junctions embedded in a coplanar transmission line has been studied. The current-voltage characteristics of Josephson structures fabricated using various technologies are studied: in-situ and ex-situ with annealing in an oxygen atmosphere. The results obtained can be used to create a quantum ac voltage generator based on high-temperature Josephson junctions.

The disorder effect on superconducting properties of thin-film YBCO nanostructures in external magnetic fields is experimentally studied. The disorder was produced by irradiation with xenon ions. The research included transport measurements of narrow bridges based on HTSC YBCO films (thickness 50 nm) in strong magnetic fields (up to 12 T). Thus, for samples with different degrees of disorder, critical dependences have been studied, i.e. the H c2 (T) phase-transition line, the H irr (T) irreversibility line, etc. The dependences of the mean-free path and critical temperature on the concentration of defects created by ion irradiation have been experimentally studied. The experimental data are described using formulas obtained within the framework of well-known models, such as the Ginzburg-Landau theory, the Drude theory, and the Gorkov equations. Keywords: B HTSP, thin films, ion irradiation, defects, resistive measurements, upper critical field, line of irreversibility, vortices.

This work is devoted to the study of epitaxial YBCO films obtained by laser sputtering during deposition of YBCO into the windows of the special preliminary topology mask. The morphology of the surface of the obtained structures was studied by electron microscopy, the electrical characteristics of superconducting bridges were measured: the critical temperature and the critical current density. The possibility of forming YBCO structures of a given topology with defect-free regions of micron sizes while maintaining high electrophysical parameters of the superconductor is shown. This opens up the possibility of reproducibly forming submicron-scale elements in the created defect-free areas using ion etching or ion implantation. Keywords: nano- and microstructures, defects, growth in local areas, YBCO.

This study is devoted to the investigation of the electrophysical parameters of superconducting and insulating elements of planar structures manufactured by master mask based on the high-temperature superconductor YBa2Cu3O7 – d with a decrease in the size of the elements to values of the order of one micrometer. Using standard photolithography, the method of master mask was used to obtain structures with superconducting elements with the width of 2 μm and parameters sufficient for instrumental applications.

This article is devoted to the study of the electrophysical parameters of superconducting and insulating elements of planar structures manufactured by the preliminary topology mask method based on the high-temperature superconductor YBa2Cu3O7-d, when the size of the elements is reduced to values of the order of one micrometer. Using standard photolithography by the preliminary topology mask method, structures with superconducting elements with a width of 2 microns and parameters sufficient for instrument applications are obtained.

When manufacturing YBCO structures using traditional methods, a certain compromise is usually reached, namely: films with the relevant morphology, but with low electrophysical parameters are used. In this paper, it is shown that YBCO bridges 4 μm in width with the perfect surface morphology, i.e., without defects, with the critical current density Jc ≥ 3 × 106 A/cm2 at temperature 77 K and critical temperature Tc  ≥  88 K can be obtained using the master mask method. The perfect morphology of the bridge surface, values of the critical current density and critical temperature are retained even after the repeated (additional) deposition of the YBCO layer onto the structure with the master mask. The results obtained from the experiments with fifteen samples suggest that, unlike electrophysical characteristics, the fixation of the standard (basic) parameters of the growth process is not sufficient to obtain the perfect morphology of the YBCO film surface.