Superconductor YBa2Cu3O7-δ Research Articles

Effect of Proton Irradiation on Thin-Film YBa2Cu3O7-δ Superconductor.

We investigated the effect of 0.6 MeV proton irradiation on the superconducting and normal-state properties of thin-film YBa2Cu3O7-δ superconductors. A thin-film YBCO superconductor (≈567 nm thick) was subject to a series of proton irradiations with a total fluence of 7.6×1016 p/cm2. Upon irradiation, Tc was drastically decreased from 89.3 K towards zero with a corresponding increase in the normal-state resistivity above Tc. This increase in resistivity, which indicates an increase in defects inside the thin-film sample, can be converted to the dimensionless scattering rate. We found that the relation between Tc and the dimensionless scattering rate obtained during proton irradiation approximates the generalized d-wave Abrikosov-Gor'kov theory better than the previous results obtained from electron irradiations. This is an unexpected result, since the electron irradiation is known to be most effective to suppress superconductivity over other heavier ion irradiations such as proton irradiation. In comparison with the previous irradiation studies, we found that the result can be explained by two facts. First, the dominant defects created by 0.6 MeV protons can be point-like when the implantation depth is much longer than the sample thickness. Second, the presence of defects on all element sites is important to effectively suppress Tc.

Триплетные сверхпроводящие корреляции гибридной меза-структуры с двухслойной ферромагнитной прослойкой

We present results on electron transport in hybrid Josephson mesa-structure Sd/F1F2/S, consisting of epitaxial films of cuprate superconductor YBa2Cu3O7-δ (Sd), bi-layer ferromagnetic interlayer (F1F2), thin film of metallic Nb was deposited on the top of a thin protective Au film layer used as the upper superconducting electrode (S). The long-range triplet component of superconducting correlations arises when strontium ruthenate SrRuO3 F1 and manganiteLa0.7Sr0.3MnO3 with non-collinear magnetizations are used as ferromagnetic material F2. Superconducting current took place up to the thickness d = 52 nm of the F1F2 interlayer. Superconducting current disappeared in the case of a single ferromagnetic interlayer of manganite (La0.7Sr0.3MnO3 or La0.7Ca0.3MnO3) and SrRuO3 with minimized thicknesses, limited by the occurrence of pinholes. The magnetic field properties of mesa-structure are discussed as well, along with the impact of the second harmonic in the superconducting current-phase relation.

Temporal Evolution of Defects and Related Electric Properties in He-Irradiated YBa2Cu3O7-δ Thin Films.

Thin films of the superconductor YBa2Cu3O7-δ (YBCO) were modified by low-energy light-ion irradiation employing collimated or focused He+ beams, and the long-term stability of irradiation-induced defects was investigated. For films irradiated with collimated beams, the resistance was measured in situ during and after irradiation and analyzed using a phenomenological model. The formation and stability of irradiation-induced defects are highly influenced by temperature. Thermal annealing experiments conducted in an Ar atmosphere at various temperatures demonstrated a decrease in resistivity and allowed us to determine diffusion coefficients and the activation energy ΔE=(0.31±0.03) eV for diffusive oxygen rearrangement within the YBCO unit cell basal plane. Additionally, thin YBCO films, nanostructured by focused He+-beam irradiation into vortex pinning arrays, displayed significant commensurability effects in magnetic fields. Despite the strong modulation of defect densities in these pinning arrays, oxygen diffusion during room-temperature annealing over almost six years did not compromise the signatures of vortex matching, which remained precisely at their magnetic fields predicted by the pattern geometry. Moreover, the critical current increased substantially within the entire magnetic field range after long-term storage in dry air. These findings underscore the potential of ion irradiation in tailoring the superconducting properties of thin YBCO films.

TMR-high-temperature superconductor composite magnetic sensor and its performance optimization

Tunnel magnetoresistance (TMR), recognized for its high sensitivity and low power consumption, holds significant promise in the domain of weak magnetic field detection. Using superconducting materials as magnetic concentrators can achieve several hundred to even a thousandfold amplification of magnetic fields, making it one of the most effective approaches to enhance the magnetic field resolution of TMR sensors. This paper utilized the flip-chip bonding process to integrate TMR with the high-temperature superconductor YBCO (YBa2Cu3O7-δ), and successfully developed TMR-YBCO composite magnetic sensor. Building upon this foundation, through optimization of the fabrication process and the pioneering use of a structural design incorporating the filling of annular holes with superconducting concentrators, the sensitivity of the sensor was further enhanced. Finally, the magnetic field resolution was increased by 1030 times compared to TMR sensors, reached to 2.9pT/Hz1/2 at 1 Hz. Simultaneously, results from frequency band testing indicated excellent frequency band characteristics, with a frequency response range exceeding kHz.

Orthorhombic YBa2Cu3O7−δ Superconductor with TiO2 Nanoparticle Addition: Crystal Structure, Electric Resistivity, and AC Susceptibility

This article reports the effect of a nanoscale addition of TiO2 on the structure and superconducting parameters of the high-temperature superconductor YBa2Cu3O7-δ (Y123). Polycrystalline compounds of Y123 with different percentages of TiO2, x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, were fabricated using the thermal treatment method. An analysis using X-ray diffraction confirmed the formation of Y123 phases for all composite samples. Field-emission scanning electron microscopy (FESEM) analysis revealed the growth of grain size and decrease in porosity, with a sign of partial melting of grains for the samples with TiO2 addition. The magnetic and electric transport properties were investigated using AC susceptibility measurement and the four-probe method, respectively. It was observed that the superconducting transition temperature, Tc-onset, for a pure sample determined by ACS and 4PP was 95.6 K and 95.4 K, respectively. These values were found to decrease with the addition of TiO2, while the superconducting transition (∆Tc) improved with TiO2 addition except for the sample at x = 0.2 wt.%, which showed the broadest transition width. The sharpest superconducting transition (∆Tc) was observed for the sample at x = 1.0 wt.%, indicating that the addition of TiO2 nanoparticles is expected to serve as artificial pinning centres and strengthen the connection among the grains in the Y123 ceramic.

Superconducting Properties of YBa2Cu3O7-δ with a Multiferroic Addition Synthesized by a Capping Agent-Aided Thermal Treatment Method.

A bulk YBa2Cu3O7-δ (Y-123) superconductor synthesized by a thermal treatment method was added with different weight percentages (x = 0.0, 0.2, 1.0, 1.5, and 2.0 wt.%) of BiFeO3 (BFO) nanoparticle. X-ray diffraction (XRD), alternating current susceptibility (ACS), and field emission scanning electron microscopy (FESEM) were used to determine the properties of the samples. From the XRD results, all samples showed an orthorhombic crystal structure with a Pmmm space group. The sample x = 1.0 wt.% gave the highest value of Y-123. The high amounts of BFO degraded the crystallite size of the sample, showing that the addition did not promote the grain growth of Y-123. From ACS results, the Tc-onset value was shown to be enhanced by the addition of the BFO nanoparticle, where x = 1.5 wt.% gave the highest Tc value (91.91 K). The sample with 1.5 wt.% showed a high value of Tp (89.15 K). The FESEM analysis showed that the average grain size of the samples decreased as BFO was introduced. However, the small grain size was expected to fill in the boundary, which would help in enhancing the grain connectivity. Overall, the addition of the BFO nanoparticles in Y-123 helped to improve the superconducting properties, mainly for x = 1.5 wt.%.

Prediction of the resistivity of YBa2Cu3O7-δ superconductor by a highly sensitive one-dimensional phononic crystal sensor

In this research, we have theoretically introduced a new application of one-dimensional (1D) phononic crystals (PnCs) manifested as a sensor for the variations in porosity ratios of a high Tc superconductor material (Ba2Cu3O7-δ). Notably, there is a massive need for accurate detection of the changes in the porosity ratio of the YBa2Cu3O7-δ material due to the dependence of its resistivity and critical current density Jc as well on the porosity ratio. Meanwhile, the changes in the porosity ratio could be demonstrated by tuning a resonant mode in the transmission spectrum of the 1D PnC. Therefore, we considered the YBa2Cu3O7-δ as a defect layer inside the periodic design (Lead/Epoxy)N of the 1D PnC. Herein, the transfer matrix method (TMM) is used to calculate the transmission spectra of the proposed design. Our findings showed that the proposed sensor is capable of detecting and sensing the variations in the porosity ratio of YBa2Cu3O7-δ as well as indicating its mechanical properties with relatively high performance and sensitivity. Moreover, the obtained results have unfolded a very sensitive effect in the resonant peak position based on the physical properties of YBa2Cu3O7-δ. Since the position of the resonant peak is highly sensitive to the smallest changes in the porosity ratio. Finally, the investigated sensitivity and quality factor can reach the values of 75.04 kHz and 186.474, respectively, for a 1% change in the porosity of YBa2Cu3O7-δ. In a nutshell, it's a new way of correlating the mechanical properties of a porous high Tc superconducting material based on the porosity ratio that may be used in various industrial and technological applications.

Investigation of structural and Magnetic properties of (Nb) Substituted YBCO-system

In this study, we report the synthesis and characterization of YBa2Cu3O7-δ (YBCO) high temperature superconductor prepared by solid state method and doped with Nb in different weight percentages, 0, 0.01, 0.02 and 0.05 wt%. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic phase of superconductivity for all the prepared samples. We evaluated the effects of Nb doping on the normal state resistivity (ρ), superconducting transition temperature (Tc), scanning electron microscope (SEM. The critical current densities, JC as a function of temperature have been calculated using the critical state model from the hysteresis loops up to 1T at temperature range of 10K to 60K. Magnetic flux pinning, FP of samples was calculated by using Lorentz force. XRD analysis show a shorter c axis parameter and higher orthoromthcity than the pure Y-123 and other Nb doped samples. It was also found from critical current density and magnetic flux pinning force measurement the 0.01 wt% Nb substation for Y on YBCO superconductors improve the critical current density and flux pinning force.

Study of Energy Dissipation in the Mixed-State YBa2Cu3O7-δ Superconductor with Partially Deoxygenated Structures.

Energy dissipation from vortex motion, which appears as a resistivity of the mixed-state superconductor, limits the range of type II superconductors in low- and high-power electronics and optoelectronics. The level of dissipation increases with the development of the vortex motion phase from that of the thermally activated flux flow to that of the flux creep and finally to that of the flux flow. The vortex motion regimes depend on the balance between bias current-self-produced Lorentz force, accelerating vortices, and the pinning force, which, together with a magnetic drag force from pinned vortices, tends to stop the vortex motion. The current paper reports on energy dissipation in YBa2Cu3O7-δ (YBCO) devices provided with partially deoxygenated structures mutually interacting by magnetic force with one another. The shape of the structure and the magnetic interaction between the trapped and moving vortices, as well as the magnetic interaction between neighboring structures, can cause the appearance of voltage steps in the device’s current–voltage characteristics observed in temperature range 0.94 ≥ T/Tc ≥ 0.98 (here, Tc = 91.4 K is the temperature of the superconducting transition in the YBCO material). Current findings demonstrate the potential of artificial structures to control vortex motion in a mixed-state YBCO superconductor by means of a temperature, bias current, and a specific configuration of the structure itself and a profile of the oxygen distribution in it.

Intergrain connectivity in YBa2Cu3O7-δ superconductor added with Dy2O3 nanoparticles: AC susceptibility investigation

YBa2Cu3O7-δ (or YBCO) superconductors added with various concentrations of dysprosium oxide nanoparticles (NP-Dy2O3) were prepared using the solid-state process. The additive NP-Dy2O3 has a size of about 10 nm and presents a para/ferromagnetic transition at about 300 K. The characterization of samples was probed via XRD, TEM, SEM, DC magnetization, and AC susceptibility measurements. Some models were employed to compute superconducting parameters like intragranular critical current density under a magnetic field (Jcm(H)), the density of intragranular pinning force for Abrikosov vortex (εg(0)), intergranular critical current density (Jc,inter), intergranular electrical character, superconductor grain volume fraction (fs). The correlation between these parameters and microstructure was discussed. The inclusion of NP-Dy2O3 does not alter the structural properties and the spatial growth of YBa2Cu3O7-δ. NP-Dy2O3 addition led to significant enhancements of Jcm(H) and εg(0). The decrement in Jc,inter was attributed to the change of grain boundary characteristics that transformed from SNS to SINS junction due to NP-Dy2O3 addition.

Tuning of superconducting phase transition and magnetic properties of ferroelectric-superconducting PbZr0.48Ti0.52O3/YBa2Cu3O7-δ heterostructure

Tuning of superconducting phase transition temperature (Ts) and interfacial magnetism is of great technological importance for micro and nanoelectronics. To achieve the cherished goal, an ultra-thin layer (4 nm, 6 nm, 8 nm 10 nm) of ferroelectrics PbZr0.48Ti0.52O3 (PZT) on high-temperature superconductor YBa2Cu3O7-δ (YBCO) has deposited to tailor the magnetic and superconducting properties. The existence of Meissner effect confirmed the superconducting nature of YBCO in the heterostructures. However, its Ts significantly shifted to the lower temperature side with an increase in PZT capping layers' thickness. Nearly 10 K reduction in Ts was observed with an increase in the capping layer from 4 to 10 nm. A significant amount of magnetic moment was found in the heterostructures, which increases almost three times compared to the YBCO/LAO magnetic moment above Ts. We believe novel weak magnetic phases above the Ts may be due to the re-arrangement of oxygen anion near the ferroelectric-superconducting interface.

Texture and terahertz analysis of YBa2Cu3O7 grown onto LaAlO3 by the chemical solution deposition technique

ABSTRACT We analyze in-plane and out-of-plane texture and terahertz analysis of a YBa2Cu3O7-δ (YBCO) film deposited by chemical solution deposition technique onto LaAlO3 (100) substrate. X-ray diffraction reveals the presence of (00l) reflections for the YBCO phase. The out-of-plane texture, measured by a rocking curve, shows two sub-layers with Δω = 0.45° and 1.8°. The value of the c-axis fraction of the crystallites is 81%. Also, the in-plane texture was studied by ϕ–scan measurements of (102) reflection, displaying mostly a colony of c-axis oriented grains, and two colonies of a-axis oriented grains onto the YBCO surface. In addition, the temperature dependence of the magnetization measurement revealed a critical temperature of 90 K, typical for YBCO superconductor material. From the temperature-dependent optical conductivity of YBCO, we observe an absorption feature at ≈1.57 THz, which redshifts with increasing temperature.

The effective synthesis of large volumes of the ultrafine BaZrO3 nanoparticles

BaZrO3 perovskite nanoparticles constitute a material desired for various advanced applications e.g. as artificial pinning centers in high-temperature superconductors or for photocatalytic hydrogen evolution. In this contribution, a novel method of synthetic for ultra-fine, pristine, non-stabilized free-surface nanoparticles of BaZrO3 is described. The method is based on the wet chemical approach and can yield large quantities of the desired product. The synthesized BaZrO3 nanoparticles were characterized by X-ray powder diffraction, X-ray fluorescence, and high-resolution transition electron microscopy. The analyses confirmed particle size in the range of 10–12 nm. Among its possible applications, the usage of such synthesized BZO in YBa2Cu3O7-δ superconductors is particularly interesting, because of the sizes of nano BZO, which is ideal for artificial pinning centers in single-domain YBa2Cu3O7-δ superconducting ceramics composites. The effect of YBa2Cu3O7-δ doping by BaZrO3 was studied by various measurements including morphology probed by scanning electron microscopy, measuring of trapped field, levitation force, and susceptibility of the prepared YBa2Cu3O7-δ single grain bulks. The synthesis method of ultra-fine BaZrO3 nanoparticles can be useful not only for applications in high-temperature rare-earth-based superconductors but also for a multitude of other applications also because of relative affordability and the possibility of synthesis of larger volumes of this material.

Study of transport and elastic properties of YBCO superconductor by inclusion of GnPs

The variation in superconducting and elastic parameters of YBa2Cu3O7-δ (YBCO) superconductor due to addition of Graphene nanoplatelets (GnPs) was examined. All the composite samples (1-x) YBCO + x GnPs (x = 0.1, 0.3, 0.5, 0.7 and 0.9%) were synthesized by conventional solid state reaction route. The structural and morphological characterizations of composite samples were investigated through the X-ray diffraction and FESEM analysis respectively. An improvement of superconducting transition temperature (TC) was observed with an increasing wt.% of GnPs concentration. Similarly, the critical current density (JC) was found to be increased and optimum value is found to be 892.48 A/cm2 for 0.7 wt.% GnPs added to the sample at 77 K. This may be attributed to the enhancement of superconducting volume fraction and reduction of porosity of the material under the addition of GnPs. Furthermore, to investigate the elastic parameters of the samples Vickers microhardness and Ultrasonic pulse-echo technique were utilized.

Microstructure, AC susceptibility and electrical properties of K2CO3 added YBa2Cu3O7−δ superconductor

The effect of potassium carbonate addition on YBa2Cu3O7-δ is reported. Samples with starting composition YBa2Cu3O7-δ(K2CO3)x were prepared using the solid reaction method with x = 0, 0.1, 0.3, 0.4, 0.5, 1.0 and 5.0 wt%. The four-point probe electrical resistance, AC susceptibility, X-ray diffraction method and field emission scanning electron microscopy (FESEM) were used to characterize the samples. Addition of K2CO3 did not affect the orthorhombic structure and the microstructure. The average grain size was between 12 and 13 µm and not affected by the addition of K2CO3. A slight decrease in the onset transition temperature was observed for x ≤ 1.0. The x = 5.0 wt% samples showed a significantly reduced transition temperature. Samples with x = 0 to 0.5 wt% showed a peak in the imaginary part of the complex susceptibility known as the peak transition temperature, Tp of around 85–86 K while the x = 5.0 wt% samples showed Tp reduced to 82 K . The critical current density at Tp was between 15 and 19 A/cm2. This work showed that K2CO3 and KClO3 have totally different effects on YBa2Cu3O7-δ superconductor.

Production of Sharp-Edged and Surface-Damaged Y2BaCuO5 by Ultrasound: Significant Improvement of Superconducting Performance of Infiltration Growth-Processed YBa2Cu3O7-δ Bulk Superconductors.

Growth and physical properties of bulk REBa2Cu3O7−δ (REBCO) superconductors fabricated by the infiltration growth (IG) method strongly depend on the initial size and morphology of the RE2BaCuO5 (211) particles. The present work details the novel method we developed for producing sharp-edged and surface-damaged 211 particles to be added to the REBCO bulks. We employed high-energy ultrasonic irradiation for pretreating the 211 particles and fabricated high-performance bulk single-grain YBa2Cu3O7−δ (YBCO) superconductors via the top-seeded IG process. Increasing the ultrasound irradiation power and time duration mechanically damaged the surface of the 211 particles, producing more fine and sharp edges. Systematic investigations of the microstructural properties of the final YBCO bulks indicated that the size and content of the 211 particles gradually decreased without any additional chemical doping. The effective grain refinement and improved interfacial defect densities enhanced the critical current density by a factor of two at 77 K and self-field as compared to a YBCO sample fabricated without any pretreatment. A maximum trapped field of 0.48 T at 77 K was obtained for a sample (20 mm diameter) with 211 particles treated for 60 min and 300 W ultrasound radiation. The effectiveness of the novel method is demonstrated by the superior performance of the YBCO bulk samples prepared as compared to bulk samples fabricated with the addition of Pt and CeO2. This method is novel, cost effective, and very convenient, maintaining high sample homogeneity, and is free of chemical contaminants as compared to other methods which significantly affect the properties of all REBCO bulk products grown by sintering, melt growth, and IG methods.

Increasing the Transition Temperature of High-TC Superconductor Thin Films by Organic Linking of Gold Nanoparticles

The transition temperature, TC, of two types of optimally doped cuprate high-TC superconductor films, YBa2Cu3O7-δ and La1.85Sr0.15CuO4, is found to increase upon linking Au nanoparticles to their surface via organic molecules. At the same time, and quite surprisingly, the critical current is reduced. We attribute these results to screening of the Coulomb interactions and smearing the pinning potential landscape. The transition temperature was increased also when the Au NPs were not chemically linked to the surface, consistent with the screening scenario. The linking molecules, however, enable selective adsorption of the gold nanoparticles and their separation from the surface, thus eliminating the conventional proximity effect.

Nodal superconducting exchange coupling.

A superconducting spin valve consists of a thin-film superconductor between two ferromagnetic layers. A change of magnetization alignment shifts the superconducting transition temperature (ΔΤc) due to an interplay between the magnetic exchange energy and the superconducting condensate. The magnitude of ΔΤc scales inversely with the superconductor thickness (dS) and is zero when dS exceeds the superconducting coherence length (ξ). Here, we report a superconducting spin-valve effect involving a different underlying mechanism in which magnetization alignment and ΔΤc are determined by nodal quasiparticle excitation states on the Fermi surface of the d-wave superconductor YBa2Cu3O7-δ sandwiched between insulating layers of ferromagnetic Pr0.8Ca0.2MnO3. We observe ΔΤc values that approach 2 K with the sign of ΔΤc oscillating with dS over a length scale exceeding 100ξ and, for particular values of dS, the superconducting state reinforces an antiparallel magnetization alignment. These results pave the way to all-oxide superconducting memory in which superconductivity modulates the magnetic state.

AC susceptibility investigation of YBCO superconductor added by carbon nanotubes

We report in this investigation the preparation as well as characterization of bulk YBa2Cu3O7-δ superconductor produced by solid state reaction route and added by various amount (x) of CNTs (x = 0.0, 0.1 and 1.0 wt%). The analysis of X-ray diffraction (XRD) indicated the achievement of orthorhombic structure of YBCO phase for various sintered samples. No relevant variations in the lattice parameters is observed with CNTs inclusion. The analysis of microstructure revealed a dispersion of CNTs into YBCO and presence of lattice defects for CNTs added samples. We evaluated the impacts of CNTs on inter-granular traits of YBCO using AC susceptibility measurements. Various superconducting parameter including critical temperature (Tc), inter-granular critical current density (Jc inter), grain volume fraction (fg), grains susceptibility (χg) and matrix susceptibility (χm) were estimated and deeply discussed. The obtained results confirm that the CNTs addition has a beneficial role on the inter-granular properties of YBCO system. Also, the critical current density Jcm was determined and its value has been shown to be greatly enhanced with the addition of CNTs in the existence of the applied magnetic field.

Measurements of phase shifts in YBCO transmission lines for evaluation of kinetic inductance change

We fabricated a coplanar waveguide (CPW) using high temperature superconductor YBa2Cu3O7-δ (YBCO) and evaluated its characteristics for the realization of a superconducting parametric amplifier. A YBCO thin film with a film thickness of 200 nm was formed by the PLD method using a YAG laser on a 10 × 10 mm MgO substrate. The YBCO thin films were processed into the CPW shape with a line width of 8 μm, a gap width of 8 μm and a line length of 5 mm by photolithography and sputter etching. Using a network analyzer, phase differences of microwave were measured at dc current bias from 0 mA to 14 mA. From the measurement results, it was found that the phase difference decreased with increasing temperature. In addition, it was found that the phase shifts greatly varied near the superconducting transition temperature at each current bias. We observed a maximum phase difference Δθ of -0.08 rad at a bias current of 14.0 mA, which is the closest to the transition temperature. A parametric gain was estimated to be 0.15 dB from the measured maximum phase difference.