Evgeny Stepantsov

Evgeny Stepantsov
Russian Academy of Sciences | RAS · Institute of Crystallography

PhD

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125
Publications
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Publications

Publications (125)
Article
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YBa2Cu3O7 − x films of b orientation have been grown on the surface of (100)SrLaGaO4 crystal. It is demonstrated that the films pass to the superconducting state at a temperature of 89 K. In the nonsuper-conducting region, the film resistance decreases linearly with a decrease in temperature at a rate of 30 Ω per 100°C. According to the X-ray diffr...
Article
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The structure of Fe1 + δTe1 − x Sex films (x = 0; 0.05) grown on single-crystal MgO and LaAlO3 substrates has been investigated by transmission and scanning transmission electron microscopy. The study of Fe1.11Te/MgO structures has revealed two crystallographic orientation relationships between the film and substrate. It is shown that the lattice m...
Article
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Thin films of iron-based chalcogenide superconductors FeSe0.92, with iron partially replaced (at least up to 10 at %) by elements such as cobalt, nickel, manganese, or copper, have been grown on the surface of \((10\bar 12)\) LaAlO3 crystals. Growth is performed by the laser ablation of a target prepared in the form of a ceramic pellet by high-temp...
Article
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Thin films of FeSe0.92 and FeSe0.5Te0.5 iron chalcogenide superconductors and solid solutions containing these components in different ratios have been grown on the surface of LaAlO3 (10 2) crystals by pulsed laser deposition. Films of solid solutions have been deposited by simultaneous laser ablation from two targets of the FeSe0.92 and FeSe0.5Te0...
Article
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In this paper we present the results of structural, optical, magnetooptical and magnetoresistive studies of La2/3Ca1/3MnO3/La2/3Sr1/3MnO3 and La2/3Ca1/3MnO3/SrTiO3/La2/3Sr1/3MnO3 heterostructures deposited on (100) SrTiO3 substrates. The results point out that magnetorefractive effect in magnetoreflection and magnetotransmission modes reaches large...
Article
YBa2Cu3O7 films with CuO planes tilted to the surface have been grown on SrTiO3 crystals by pulsed laser deposition. The tilt angle was varied in the range from 0° (CuO planes are parallel to the surface) to 70°. At this tilt, the crystalline lattice of the film was rotated by rotating the substrate crystalline lattice around its axis [100], which...
Article
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YBa2Cu3O7 films with the CuO plane tilted to the surface have been grown on SrTiO3 crystalline substrates by pulsed laser deposition. This tilt was obtained by rotating the film lattice with respect to the substrate surface around its [110] axis oriented parallel to the surface. The zero tilt of the CuO plane was implemented at the orientation of t...
Article
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The effect of both the film-film interface and the SrTiO3 interlayer on the magneto-optical and magnetotransport properties of La2/3Ca1/3MnO3-La2/3Sr1/3MnO3 heterostructures, depending on the direction of external magnetic field, was studied. It is shown that the interface boundary makes a contribution characteristic of a manganite of intermediate...
Article
The optical, magnetooptical (Kerr effect and magnetotransmission), and magnetotransport properties of La2/3Ca1/3MnO3/La2/3Sr1/3MnO3 and La2/3Ca1/3MnO3/SrTiO3/La2/3Sr1/3MnO3 heterostructures on SrTiO3 substrates are studied. The contribution of the interface boundary to the magnetotransmission is typical of a material with a transitional composition...
Article
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Bicrystal Josephson junctions and direct current superconducting quantum interference devices (dc SQUIDs) were prepared on YBa2Cu3O7 (YBCO) thin films deposited on yttrium stabilized ZrO2 bicrystal substrates. The critical current densities Jc similar 2 × 106 A/cm2 for YBCO thin film and (1 - 3) × 103 A/cm2 at boundaries were obtained at 77 K. For...
Article
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In YBa2Cu3O7 − x films grown on sapphire bicrystal substrates, the Josephson junctions are prepared based on artificial grain boundaries formed by the turn of the crystal lattices about the [100] axis. The films are deposited by the laser ablation method on the buffer CeO2 layer. The critical film temperature reaches 88.5 K with a transition width...
Article
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The possibility of preparing bicrystalline Josephson junctions and bolometers based on superconducting MgB2 on specially prepared bicrystalline MgO substrates is investigated. Microbridges 0.85–6.00 μm in width, intersecting the bicrystalline interface, are formed in epitaxial bicrystalline MgB2 films grown on these substrates. It is found that ann...
Article
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The authors have fabricated the MgB2 bridges 850–6000 nm in width on bicrystal (111) MgO substrates with in-plane grain boundaries of the two types: 13°/13° ⟨110⟩ and 13°/13° ⟨112⟩. Annealing in oxygen of the films on ⟨110⟩ bicrystal substrates leads to a systematic decrease of critical current, a widening of the transition temperature width, and a...
Article
Potentialities of Solid Phase Intergrowing (SPI) of crystals [5] in conformity with the investigations of HTSC are discussed. In particular the application of SPI for creation of dielectric crystalline substrates containing model boundaries (low- or high-angle, single or multiple) perpendicular to their surfaces is analyzed. Both HTSC film structur...
Article
The properties of YBa2Cu3O7-δ dc-SQUIDs (superconducting quantum interference devices) with 0°-45° grain boundary junctions have been studied. Structures fabricated on two types of bicrystals have been investigated: The conventional [001]-tilt type and a novel configuration with both [001] and [100] tilt. Measurements have been performed in the tem...
Article
We have measured the transport properties of YBa2Cu3O7−δ (YBCO) dc SQUIDs with Josephson junctions characterized by a combination of 45° [0 0 1] tilt and α [1 0 0] tilt grain boundary with α = 0°, ±10° and 45°. By increasing the component of transport in the YBCO c-axis direction (increasing values of α), the SQUIDs showed an enhanced quality facto...
Article
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For sensitive wideband spectroscopy at TeraHertz frequencies one needs a wide-range electrically tunable THz source and a sensitive detector. In this paper a superconducting normal metal cold electron bolometer (CEB) was used as a broadband sensor. Bolometers were integrated with broadband log-periodic antenna designed for 0.2-2 THz frequency range...
Article
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For sensitive wideband spectroscopy at TeraHertz frequencies one needs a wide-range electrically tunable THz source and a sensitive detector. In this paper a superconducting normal metal cold electron bolometer (CEB) was used as a broadband sensor. Bolometers were integrated with broadband log-periodic antenna designed for 0.2-2 THz frequency range...
Chapter
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We have developed a low temperature transmission spectrometer operating in a wide range of frequencies from 100 GHz to 1.7 THz. The spectrometer has utilized unique properties of high-Tc superconducting Josephson junctions and wideband response of sensitive Cold-Electron Bolometers (CEB). The voltage response of the CEB integrated with log-periodic...
Article
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Superconducting Josephson junctions with high characteristic voltages (IcRn larger than 4 mV at 4.2 K) are fabricated by depositing YBa2Cu3O7−x on tilted sapphire bicrystal substrates, where the tilting axis is along the grain boundary. The good junction quality and low microwave losses in sapphire gave high frequency response well into the THz reg...
Conference Paper
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For sensitive wideband spectroscopy at THz frequencies with performance better than for Fourier Transform Spectrometer, one needs a wide-range electrically tunable, narrow linewidth THz source, and a sensitive broadband detector. To obtain a low noise level of sensor we use a superconducting normal metal cold electron bolometer (CEB). A voltage res...
Conference Paper
Full-text available
We have demonstrated a low temperature spectrometer operating in a wide range of frequencies from 100 GHz to 1.8 THz. The spectrometer has utilized unique properties of high-T c superconducting Josephson junctions and wideband response of sensitive Cold-Electron 13olometers (CEB). The voltage response of the CEB integrated with log-periodic and dou...
Article
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The voltage response of a thin-film normal-metal hot-electron bolometer based on a SINIS (superconductor-insulator-normal metal-insulator-superconductor) structure to the radiation of a high-temperature Josephson junction in the terahertz frequency region was measured. Bolometers were integrated with planar log-periodic and double-dipole antennas,...
Article
We report on depairing critical currents in submicron YBa2Cu3O7−δ microbridges. A small-angle bicrystal grain boundary junction is used as a tool to study the entrance of vortices induced by a transport current and their influence on the I–V curves. The interplay between the depairing and the vortex motion determines a crossover in the temperature...
Conference Paper
We have studied the very high frequency response of high critical temperature Josephson junctions. High quality YBa2Cu3O7-x epitaxial films were fabricated by pulsed laser deposition on tilted (vicinal) sapphire substrates with CeO2 buffer layers. YBaCuO films have smaller tilt angles, from 1.0o up to 10.3o, compared to inclination angles of the su...
Article
In this paper we examine the state-of-the-art patterning techniques for fabrication of ultrasmall bicrystal Josephson junctions in YBa2Cu3Ox. We determine the dependence of junction parameters---critical current, characteristic voltage IcRn, and capacitance---on its size. Using the values of the Josephson and the Coulomb energies extracted from exp...
Article
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Most proposed realizations of a high temperature superconductor (HTS) qubit require the use of very small Josephson junctions. The properties of bicrystal junctions are especially interesting since they make it possible to implement several types of flux qubits in a relatively simple way. We have developed a technique that allows us to produce high...
Article
Submicron YBCO bicrystal Josephson junctions (JJ) and devices for high frequency applications were designed, fabricated and experimentally studied. The key elements of these devices are bicrystal sapphire substrates with symmetric misorientation angles 14.2°, 18.4° and 24° which were fabricated by a solid-state intergrowth method. A technological p...
Article
YBCO integrated structures consisting of a planar antenna and a Josephson junction were designed and fabricated on bicrystal sapphire substrates. By combining two such structures in an oscillator-receiver arrangement a submillimeter- wavelength tester was realised. Two types of relatively narrow-band double-slot and double-dipole antennas, a broadb...
Article
A novel approach to synchronization of arrays of Josephson junctions (JJA) is proposed. Each Josephson junction is placed in the center of a separate dipole antenna. Antennas at a distance of about a half wavelength from each other form a beam pattern with the main lobe perpendicular to the substrate plane. Two types of JJA were fabricated on YZrO2...
Article
The dependence of the superconducting current Is on the phase difference φ between the order parameters of the two superconductors forming a Josephson junction (current phase relation - CPR) determines dynamic parameters of the Josephson junctions (JJ) such as the Josephson inductance, the microwave impedance, the spectrum of the Josephson generati...
Article
An experimental investigation of high-temperature dc SQUID amplifier connected in series with a high-Tc superconductor (HTS) thin-film band-pass filter is presented. The SQUID amplifiers are designed with microstrip input coils and fabricated on bicrystal substrates of zirconia and sapphire with different misorientation angles of 24� and 37�. SQUID...
Conference Paper
We have developed a technology that makes it possible to fabricate sub-micron structures in YBa2Cu3O7- in a well controlled process. We have used this technology to fabricate Josephson junctions and SQUIDS on various crystal substrates using Grain Boundary Junction (GBJ) technology. We have characterized the properties of these structures in a temp...
Article
Full-text available
Integrated quasioptical submillimeter-wave oscillators based on high-temperature superconductor (HTSC) Josephson junctions on a bicrystal boundary are designed, fabricated, and experimentally investigated. The junctions are integrated with three types of planar antennas: log-periodic, double-dipole, and double-slot. To increase the radiated power,...
Article
Full-text available
The propagation of microwave radiation through YBa<sub>2</sub>Cu <sub>3</sub>O<sub>7-δ</sub> and Tl<sub>2</sub>Ba<sub>2</sub>Cu<sub>1</sub>O<sub>6</sub> films deposited on Al<sub>2</sub>O<sub>3</sub>, MgO, LaAlO<sub>3</sub> and LaSrAlTaO single crystal substrates, as well as through the bare substrates, has been studied in the 60-600 GHz frequency...
Article
The electrical properties of junctions at symmetrical bicrystal boundaries in high-T c superconducting films are studied as functions of the misorientation angle in the range 8–45. The junctions are prepared by growing YBa2Cu3O7 (YBCO) epitaxial films on Y-ZrO2 (YSZ) bicrystal substrates. The proportional relationship between the characteristic vo...
Article
The structure of yttrium-stabilized ZrO2 (YSZ) bicrystals with ZnO and ZnO/YSZ/ZnO/YSZ/ZnO intermediate layers, as well as ZnO films grown on YSZ bicrystal (1 1 0)/90° substrates, has been investigated by means of high-resolution electron microscopy (HREM) and microanalysis. All bicrystals were produced by the solid-phase intergrowth (SPI) method....
Article
Full-text available
An integrated amplifier based on a high-Tc DC SQUID with a microstrip input coil is designed for the frequency range 1-2 GHz. Fabrication technology of the amplifier on a bicrystal substrate is developed. A mathematical model of the device is suggested, and its performance data are computed
Article
Dependences of the amplitudes of the harmonic and subharmonic Shapiro steps on an external monochromatic signal were used to study the current-phase dependence of high-temperature superconducting junctions on a bicrystal substrate. It is shown that for a symmetric definition of the transport current across the junction with an edge transparency of...
Article
Full-text available
A breadboard Josephson submillimeter-wave mixer is designed and investigated. The best value of the mixer noise temperature for this device has been demonstrated as 1100 K at frequencies of 400-500 GHz. Josephson mixers are shown to be promising and competitive with Schottky-barrier diodes (SBDs). Excess noise associated with the multiple Andreev r...
Conference Paper
Full-text available
A HTS Josephson spectrometer has been designed, fabricated and experimentally studied. The spectrometer circuit consists of a YBCO bicrystal Josephson junction integrated with a double-slot or log-periodic antenna and connected in parallel with a gold low-inductance shunt. The YBCO films were deposited by laser ablation on sapphire and MgO bicrysta...
Conference Paper
Full-text available
We have designed and tested a topology of a HTS dc SQUID amplifier with a microstrip-type input coil on a bicrystal substrate. A process of fabrication the integrated multilayer YBCO dc SQUID amplifier was developed. The manufactured SQUIDs showed no degradation after input coil fabrication and revealed high performance properties.
Article
Full-text available
A Josephson high-temperature superconducting (HTSC) submillimeter-wave spectrometer is designed, built, and experimentally investigated. The integrated detection structure of the spectrometer includes a YBCO Josephson junction on a bicrystalline boundary, a double-slot or log-periodic antenna, and a low-inductance resistive shunt. The selective det...
Data
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Разработан, изготовлен и экспериментально исследован джозефсоновский высокотемпературный сверхпроводящий (ВТСП) спектрометр субмиллиметровых волн. Интегральная приемная структура спектрометра включает YBCO джозефсоновский переход на бикристаллической границе, двухщелевую или логопериодическую антенну и низкоиндуктивный резистивный шунт. Селективный...
Article
Full-text available
A Josephson quasioptical detector comprising YBaCuO junction on bicrystal MgO substrate, integrated log-periodic Au antenna, MgO extended hyperhemisphere lens attached to the substrate and 1.4 GHz cold amplifier with cold circulator has been designed, fabricated and experimentally studied. We fabricated several integrated Josephson junctions 1-2 μm...
Article
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We report on our experimental studies of high-T<sub>c</sub> Josephson mixers and high-T<sub>c</sub> hot-electron bolometric (HEB) effect mixers. Mixers based on high-T<sub>c</sub> bicrystal Josephson junctions have been fabricated, and noise, conversion efficiency, and receiver bandwidth measurements have been performed in the frequency range betwe...
Article
Full-text available
An HTS Josephson spectrometer has been designed, fabricated and experimentally studied. The spectrometer circuit consists of a YBCO bicrystal Josephson junction integrated with a double-slot or log-periodic antenna, connected in parallel with a gold low-inductance shunt. The selective detector response and RF response at intermediate frequency f IF...
Article
The three-terminal devices Ag/Pb(ZrxTi1−x)O3/YBa2Cu3O7−δ(Ag/PZT/YBCO) have been fabricated onto (100) SrTiO3 by pulsed laser deposition technique and photolithography. For the purpose of application, we specially selected the PZT layer with morphotropic phase boundary composition as the gate to lower the coercive fields and decrease the operating v...
Article
High-temperature superconducting Josephson junctions on bicrystal sapphire substrates were fabricated and investigated experimentally. The critical parameters of the junctions satisfy the constraints for the design of devices in the millimeter and submillimeter wavelength ranges. The results of dynamic measurements show that in these junctions the...
Article
Full-text available
Weak links were fabricated by pulsed laser deposition of YBa2Cu3Ox thin films on Y-ZrO2 bicrystal substrates. They were formed by transferring the bicrystal boundary into the epitaxial film during the film growth. Their properties were determined by the misorientation angle ( theta ) between the two halves of the bicrystal. The transport properties...
Article
Full-text available
High critical temperature Josephson mixer of submm-waves has been fabricated and studied. The best value of noise temperature was 1100 K in the frequency range 400-500 GHz.
Article
High temperature junctions are suitable for microwave generation at frequencies approaching 1 THz. Fundamental phase locking in the frequency range from 200 GHz to above 1 THz, where the bandwidth is determined by the liquid crystal resonator was observed. The measured maximum locking current IL/Io = 7% is in excellent agreement with theory. Harmon...
Article
The structure of yttrium stabilized ZrO2 crystals with intermediate seam layers of CeO2 and SrTiO3 has been studied by transmission electron microscopy (TEM). Such crystals were fabricated by the solid phase intergrowth method (SPI). The interfaces between ZrO2 and CeO2 layers were blurred compared to the sharp interfaces between CeO2 and SrTiO3 la...
Conference Paper
Full-text available
We report on our experimental studies of noise properties and conversion efficiency of high-T<sub>c</sub> Josephson mixers and high-T <sub>c</sub> hot-electron bolometric (HEB) effect mixers at frequencies between 90 GHz and 550 GHz. Noise measurements using a Josephson mixer at 90 GHz gave noise temperatures of 2900 K at 20 K. Measurements in a qu...
Article
Full-text available
We report on experimental studies of the noise performance and conversion efficiency of high-Te Josephson mixers at frequencies between 90 GHz and 550 GHz. The heterodyne mixing experiments have been performed by using YBa2Cu307_8 step-edge junctions and bicrystal junctions on MgO (E . --9.6) substrates. We studied the Josephson mixer performance f...
Article
The growth of Tl-2201 films on LaAlO3 single crystal substrates has been investigated. The synthesis involved precursor films made by laser ablation that were treated with Tl2O(g) in near-equilibrium conditions. By optimising the method of preparation, we obtained films that were highly smooth, c-axis oriented and epitaxial. The rocking curve of th...
Article
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An experimental investigation is made of the subharmonic Shapiro steps observed on the I-V curves of high-T c superconductor Josephson junctions and on the bias-voltage dependences of the rf noise and detector response when the junctions are subjected to external submillimeter radiation. Structures of this type are ordinarily described by a nonsinu...
Article
We report tunneling measurements on a large number of bicrystal YBa2Cu3O7-delta Josephson junctions. The orientations of the bicrystals relative to their boundary was varied over 80° while the misorientation angle was kept fixed at 32°. A strong anisotropy in the characteristic voltage IcRn of the Josephson junctions in the a-b plane was observed....
Article
Full-text available
The structure of the artificial grain boundaries in Al2O3 bicrystals withY3Al5O12 and Y-stabilizedZrO2 (Y-ZrO2) intermediate layers was studiedwith high resolution electron microscopy, electron diffraction and energydispersive X-ray analysis. TheY3Al5O12 intermediate layer wasfound to be polycrystalline with three different orientation relationship...
Article
The structure of different intermediate layers and their interfaces was studied in sapphire bicrystals by high resolution electron microscopy (HREM), selected area electron diffraction (SAED) and energy dispersive X-ray analysis (EDX). The intermediate layer of Y3Al5O12 between two sapphire bicrystal parts, was found to be polycrystalline with thre...
Article
Bicrystals of ZnO with large interfacial areas and controlled misorientations have been prepared by the solid-phase intergrowth method. The structure of three [0001] tilt boundaries with misorientations of less than 1°, 17·8 ± 0·1° and 31·5 ± 0·1° have been studied by high-resolution electron microscopy. The low-angle boundary comprised well separa...
Article
Tl2Ba2CuO6 (Tl-2201) thin films were synthesised on single crystal LaAlO3 and SrTiO3 substrates and on bicrystal LaAlO3 by an ex-situ process. Depending on thallium content and processing conditions, the films were orthorhombic or tetragonal. Tc was in the range 30 – 92 K while Jc reached 4.106A/cm2 at 12 K. By oxygen depletion, Tc was increased by...
Article
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The application of ac Josephson effect to the spectroscopy of incoherent radiation with continuous spectrum brings possibility to cover a wide frequency range with a high spectral resolution. This technique is named as Hilbert spectroscopy because the measured response and recovered spectrum are related by Hilbert transformation. The main advantage...
Article
We have designed, fabricated and successfully tested three SFQ elements: a toggle flip-flop, a SFQ voltage amplifier, and an RS-flip-flop. The design uses a single superconducting layer and it is optimized by repeated computer simulations and repeated inductance calculations. The inductances are made as narrow slits of 0.5 μm width. Their values ar...
Article
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Tl-2212 thin films were grown ex situ in a two step process on a variety of substrates, including ones with artificially introduced high angle steps. Grain boundary weak links were formed on LaAlO/sub 3/ substrates with steps and on bicrystal substrates and were employed in dc SQUIDs. The white noise level of the SQUIDs was 50/spl mu//spl Phi//sub...
Conference Paper
We have designed an experiment where the Josephson barrier, in our case the misorientation angle of a bicrystal grain boundary, is kept constant, while the direction of the superconducting wave function at the barrier varies. The Josephson current in these junctions is strongly anisotropic. The characteristic voltage IcRn depends on the crystal ori...
Conference Paper
Full-text available
The IV curves and the direct detector response of HTS bicrystal grain-boundary Josephson junctions have been measured under submm-wave irradiation at frequencies 350-750 GHz. The Josephson oscillation spectrum has been measured using the Hilbert transformation of detection response dependence. The Josephson oscillation linewidth and corresponding v...
Article
Superconducting epitaxial Tl2Ba2CaCu2O8 (Tl-2212) and Tl2Ba2CuO6, (Tl-2201) thin films are synthesised on single crystal and bicrystal LaAlO3 substrates by an ex-situ process. Tl-2212 films were optically smooth, with Tcs from 105 to 108K and Tc c reaching 2106A/cm2 at 77K. Tl-2201 films exhibited tetragonal or orthorhombic symmetry depending on th...
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