arXiv subjects

R. Zadorosny

Publications and source records attributed to R. Zadorosny.

9 recordsLinked to original sources

arXiv2022

Comparing energy dissipation mechanisms within the vortex dynamics of gap and gapless nano-sized superconductors

The presence of magnetic fields and/or transport currents can cause penetration of vortices in superconductors. Their motion leads to dissipation and resistive state arises, which in turn strongly affects the performance of superconducting devices such as single-photon and single-electron detectors. Therefore, an understanding of the dissipation mechanisms in mesoscopic superconductors is not only of fundamental value but also very important for further technological advances. In the present work, we analyzed the contributions and interplay of the dissipative mechanisms due to the locally induced electric field and an intrinsic relaxation of the superconducting order parameter, $Ψ$, in mesoscopic samples by using the time-dependent Ginzburg-Landau theory. Although often neglected, we show that the dissipated energy due to relaxation of $Ψ$ must be taken into account for an adequate description of the total dissipated energy. The local increase of the temperature due to vortex motion and its diffusion in the sample were also analyzed, where the joint effect of thermal relaxation and vortex dynamics plays an important role for the dissipative properties presented by the superconducting systems.

cond-mat.supr-con↗

arXiv2020

Successful production of Solution Blow Spun YBCO+Ag complex ceramics

YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mechanical and flux pinning properties of ceramic superconductors. Thus, in this work, we show how we successfully obtained a polymeric precursor solution containing YBCO$+$Ag salts, which can be spun by the SBS route to produce ceramic samples. Yttrium, barium, copper, and silver metal acetates, and polyvinylpyrrolidone (PVP) (in a ratio of 5:1wt [PVP:acetates]) were dissolved in a solution with 61.5 wt\% of methanol, 12 wt\% of propionic acid, and 26.5 wt\% of ammonium hydroxide, together with 6 wt\% of PVP in solution. Three different amounts of silver (10 wt\%, 20 wt\%, and 30 wt\%) were used in YBa$_2$Cu$_3$O$_{7-x}$. The TGA characterizations revealed a lowering of crystallization and partial melting temperatures by about \SI{30}{\celsius}. SEM images show that after burning out the polymer, a fabric composed of nanowires of diameters up to \SI{380}{\nano \metre} is produced. However, after the sintering process at \SI{925}{\celsius} for \SI{1}{\hour}, the nanowires shrink into a porous-like sample.

physics.app-ph↗

arXiv2019

Dynamical regimes of ultrafast kinematic vortices in the resistive state of mesoscopic superconductors

A superconducting state coexists with static electrical fields under the formation of phase-slips and kinematic vortices (kV 's). Besides that, such a resistive state installed in the superconductor is not desirable in many applications. Then, it is essential to know the ultrafast kV dynamics for controlling the fluxonics of the system. Thus, in this work, we studied the dynamics of the kV 's in a mesoscopic superconductor under the influence of external magnetic fields (H) and transport currents (Jtr). As a result, the kV dynamics are affected by increasing H. With those significant changes, it was possible to build a Jtr(H) phase diagram. There, in between the Meissner and the normal states, the kV 's present three distinct behaviors. For high fields, the vortices behave as Abrikosov-like ones, with velocities two orders of magnitude lower than those at low fields regime. Besides that, one demonstrates how the interplay between Jtr and the shielding currents, its controlled by H, allowing for some quantitative predictions of boundaries in the phase diagram. Additionally, for H's where only a kV is nucleated, for tenths of picoseconds, a surface barrier effect acts over the instantaneous velocity of the kV.

cond-mat.supr-con↗

arXiv2019

Solution Blow Spinning Control of Morphology and Production Rate of Complex Superconducting YBa2Cu3O7-x Nanowires

The demand for nanostructured materials can increase exponentially due to the miniaturization of devices and their potential application in different areas, such as electronic and medicine. Therefore, high production rates are essential for making nanomaterials commercially available. When electrospinning (ES) and solution blow spinning (SBS) are employed for producing ceramic nanostructures, the solution injection rate can influence the morphology without, however, supply the real ceramic production rate. In this work, complex superconducting YBa2Cu3O7-x wires were prepared by using the SBS technique. We also show that the morphology can be controlled by varying the injection rate of the polymer solution and the production rate is 4.7 to 33 times higher than the rates of equivalent ceramics produced by ES. Additionally, we also suggest the term Ceramic Production Rate to refer to the production rate of ceramic structures.

physics.app-ph↗

arXiv2017

YBCO Ceramic Nanofibers obtained by the new technique of Solution Blow Spinning

This study proposes a novel solution blow spinning technique (SBS) for fabricating YBCO ceramic nanofibers. The precursor solutions were obtained from Y, Ba, and Cu metallic acetates (Ac) and poly(vinyl pyrrolidone) (PVP, Mw = 360,000). Ac:PVP concentrations of 1:1 and 5:1 were tested, resulting in ceramic nanofibers with average diameters of 359 and 375 nm, respectively. X-ray diffraction confirmed the formation of a pure phase of YBa2Cu3O7-x. This is the first study to use SBS for fabricating YBCO nanofibers, and this technique shows promise for obtaining high-quality ceramic materials.

cond-mat.mtrl-sci↗

arXiv2013

Thermal treatment of superconductor thin film of the BSCCO system using domestic microwave oven

In this work, we report the preparation of a superconductor thin film of the BSCCO system using a good quality powder with nominal composition Bi_{1.8}Pb_{0.4}Sr_2CaCu_2O_x which was thermally treated using a domestic microwave oven (2.45 GHz, 800 W). This film was grew on a single crystal of LaAlO_3(100) substrate and exhibited a crystalline structure with the c-axis perpendicular to the plane of the substrate. An onset superconducting transition temperature was measured at 80 K.

cond-mat.mtrl-sci↗

arXiv2013

Study of the threshold line between macroscopic and bulk behaviors for homogeneous type II superconductors

In this work we solved the time dependent Ginzburg-Landau equations to simulate homogeneous superconducting samples with square geometry for several lateral sizes. As a result of such simulations we notice that in the Meissner state, when the vortices do not penetrate the superconductor, the response of small samples are not coincident with that expected for the bulk ones, i.e., $4πM=-H$. Thus, we focused our analyzes on the way which the $M(H)$ curves approximate from the characteristic curve of bulk superconductors. With such study, we built a diagram of the size of the sample as a function of the temperature which indicates a threshold line between macroscopic and bulk behaviors.

cond-mat.supr-con↗

arXiv2013

Vortex-antivortex annihilation in mesoscopic superconductors with a central pinning center

In this work we solved the time-dependent Ginzburg-Landau equations, TDGL, to simulate two superconducting systems with different lateral sizes and with an antidot inserted in the center. Then, by cycling the external magnetic field, the creation and annihilation dynamics of a vortex-antivortex pair was studied as well as the range of temperatures for which such processes could occur. We verified that in the annihilation process both vortex and antivortex acquire an elongated format while an accelerated motion takes place.

cond-mat.supr-con↗

arXiv2013

Synthesis of Bi-based superconductor by microwave-assisted hydrothermal method

In this work we studied the synthesis of BSCCO-2212 superconducting phase associating a quite similar method developed by Pechini (PM) with the microwave-assisted hydrothermal method, MAH. To study the influence of MAH on the properties of BSCCO system, we synthesized two samples by such method. For one sample we used carbonates (CMAH) and for the other one we used nitrates (NMAH) as chemical reagents. We also produced a reference sample (REF) just using carbonates by PM to compare their morphological and superconducting properties. The structural properties of the samples were analyzed by scanning electron microscopy and X-ray diffraction. It can be noted that the Bi-2212 phase is predominant in all samples; MAH samples present larger grains than the REF one. However, we can observe that the magnetic behaviour of NMAH is closer to that presented by REF.

cond-mat.supr-con↗