Angle dependent molecular dynamics simulation of flux pinning in YBCO superconductors with artificial pinning sites

Paturi, P.; Malmivirta, Mika; Hynninen, Teemu; Huhtinen, H.

doi:10.1088/1361-648x/aad02b

Cited by 19 publications

(28 citation statements)

References 35 publications

(46 reference statements)

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“…The effect of nanorod diameter on YBCO c-peak has also been studied before in 25 , but unfortunately this work cannot be used to draw any conclusions if the observed effects are due to nanorod diameter or their varying amount, which is a function of nanorod diameter if concentration is kept constant. Thus, in this work we firstly study the raw effect of nanorod diameter by five different simulations that had constant number of nanorods but with varying sizes in constant applied field, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…A critical current angular dependency MD simulation, which is described comprehensively in 25 , was used to study the effects of applied field and the dimensions and concentration of the nanorods as well as to make quantitative connections between experimentally measured transport properties and nanorod microstructure in YBCO thin films. Details of the simulation model are also given in Supplementary information (SI).…”

Section: Simulationsmentioning

confidence: 99%

“…The field dependency of critical currents in BZO doped YBCO lattice has also been computationally investigated by numerically solving the Ginzburg-Landau equations in 23 , but the effect of the applied field on critical current anisotropy has not been discussed. In the paper 25 , where the validation of the molecular dynamics (MD) simulation used in this work is presented, the effect of nanorod diameter was shortly studied as a demonstration of the feasibility of the simulation, but a detailed analysis on this subject is still lacking. The simulation model has also been used in our previous work 9 to analyse critical current anisotropies in multilayer films containing both nanodots and nanorods and the effect of the splay and fragmentation of the nanorods on J c (θ)-peak in the vicinity of YBCO c-axis (c-peak) has been studied in 24 .…”

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confidence: 99%

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Self-assembled nanorods in YBCO matrix – a computational study of their effects on critical current anisotropy

Rivasto

Khan

Malmivirta

et al. 2020

Sci Rep

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In order to understand how the doping with self-assembled nanorods of different sizes and concentrations as well as applied magnetic fields affect the critical current anisotropy in YBa 2 cu 3 o 7−x (YBCO) thin films close to YBCO c-axis, we present an extensive and systematic computational study done by molecular dynamics simulation. the simulations are also used to understand experimentally measured J c (θ) curves for BaHfO 3 , BaZrO 3 and BaSno 3 doped YBCO thin films with the help of nanorod parameters obtained from transmission electron microscopy measurements. our simulations reveal that the relation between applied and matching field plays a crucial role in the formation of J c (θ)-peak around YBCO c-axis (c-peak) due to vortex-vortex interactions. We also find how different concentrations of different size nanorods effect the shape of the c-peak and explain how different features, such as double c-peak structures, arise. In addition to this, we have quantitatively explained that, even in an ideal superconductor, the overdoping of nanorods results in decrease of the critical current. our results can be widely used to understand and predict the critical current anisotropy of YBco thin films to improve and develop new pinscapes for various transport applications.High temperature superconductors (HTS) are expected to have large number of applications in different fields of technology and power industry in the future 1-3 . Since all known HTS are of type II, the critical current passed through them is highly dependent on the surrounding magnetic field due to the movement of vortices. Thus, to enhance and widen the usability of HTS, the dynamics of vortices need to be well understood.Among the high temperature superconductors, YBa 2 Cu 3 O 7−x (YBCO) seems the most practical choice when thinking for the applications 1 . The intrinsic anisotropy of the critical current, in thin films and coated conductors, can be modified by adding impurities within the lattice of YBCO which pin the vortices restricting their movement. Based on growth conditions and lattice mismatch between the YBCO and the dopant as well as their elastic properties 4,5 , impurities such as Y 2 O 3 6 , BaCeO 3 7-9 and BaZrO 3 (BZO) 10,11 can form uncorrelated randomly distributed nanoparticles within the YBCO lattice. Under optimized deposition conditions, via a spontaneous phase-separation and strain-driven self-assembly process during film deposition 12 , self-assembly of nanorods of BaHfO 3 (BHO) 1 , BaZrO 3 (BZO) 4,13,14 , BaSnO 3 (BSO) 15,16 , Ba 2 YTaO 3 (BYTO) 17 or Ba 2 YNbO 6 (BYNO) 18 within the YBCO lattice can be realized.Recently, a topic of interest has been to add both point-like nanodots and nanorods within the YBCO lattice simultaneously. This has been achieved by doping YBCO simultaneously with both BYTO and BYNO (referred as BYNTO) with an additional rare earth oxide, leading to continuous niobiate/tantalate nanorods and rare-earth oxide nanoparticles 19 . A lot of experimental research has been done in order to understand the...

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Section: Resultsmentioning

confidence: 99%

Section: Simulationsmentioning

confidence: 99%

mentioning

confidence: 99%

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Self-assembled nanorods in YBCO matrix – a computational study of their effects on critical current anisotropy

Rivasto

Khan

Malmivirta

et al. 2020

Sci Rep

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“…However, methods like positron annihilation spectroscopy, which gives information about vacancy-type defects, are only rarely utilized on HTS thin films 14,15 . In addition to experimental scrutiny, simulations offer a way of understanding the roles that different pinning landscapes may have in explaining the angular and magnetic field dependencies of J c , as well as a method for designing the most effective pinning centers for future applications 16–18 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced flux pinning isotropy by tuned nanosized defect network in superconducting YBa2Cu3O6+x films

Khan

Rivasto

Tikkanen

et al. 2019

Sci Rep

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Striving to improve the critical current density Jc of superconducting YBa2Cu3O6+x (YBCO) thin films via enhanced vortex pinning, the interplay between film growth mechanisms and the formation of nanosized defects, both natural and artificial, is systematically studied in undoped and BaZrO3 (BZO)-doped YBCO thin films. The films were grown via pulsed laser deposition (PLD), varying the crystal grain size of the targets in addition to the dopant content. The microstructure of the PLD target has been observed to have a great impact on that of the deposited thin films, including the formation of vortex pinning centers, which has direct implications on the superconducting performance, especially on the isotropy of flux pinning properties. Based on experimentally measured angular dependencies of Jc, coupled with a molecular dynamics (MD) simulation of flux pinning in the YBCO films, we present a quantitative model of how the splay and fragmentation of BZO nanorods artifically introduced into the YBCO film matrix explain the majority of the observed critical current anisotropy.

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“…It should be noted that a universal quantitatively accurate equation for critical currents at applied magnetic field, B, is unknown to date as for intrinsic superconductors [15][16][17][18][19], as for…”

Section: Introductionmentioning

confidence: 99%

DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions and The Request for Ballistic Model Reexamination

Talantsev¹

2019

Preprint

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Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model is an inadequate tool to analyze experimental data from S/DCM/S junctions. The primary mechanism for limiting superconducting current in S/DCM/S junctions is different from the conventional view that the latter is the maximum value within the order parameter phase variation. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems.

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Angle dependent molecular dynamics simulation of flux pinning in YBCO superconductors with artificial pinning sites

Cited by 19 publications

References 35 publications

Self-assembled nanorods in YBCO matrix – a computational study of their effects on critical current anisotropy

Self-assembled nanorods in YBCO matrix – a computational study of their effects on critical current anisotropy

Enhanced flux pinning isotropy by tuned nanosized defect network in superconducting YBa2Cu3O6+x films

DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions and The Request for Ballistic Model Reexamination

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