Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Paturi, P.; Irjala, M.; Huhtinen, H.; Abrahamsen, Asger Bech

doi:10.1063/1.3066857

Cited by 30 publications

(22 citation statements)

References 34 publications

(58 reference statements)

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“…However, it should be noted that practically the overlap of the pinning potentials leads to weaker pinning between dislocations, 53 somewhat resembling the potential considered for twins as additional pinning centres in YBCO film 54 or even for the extreme regime of weaklinks applicable to coated conductors. 53 At high fields and/or temperatures, thermally activated processes play important role.…”

Section: J C (B a ) Model For Ybco Filmsmentioning

confidence: 99%

Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density

Golovchanskiy

Pan

Shcherbakova

et al. 2013

Journal of Applied Physics

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Golovchanskiy, I. A., Pan, A. V., Shcherbakova, O. V. & Fedoseev, S. A. (2013). Rectifying differences in transport, dynamic, and quasiequilibrium measurements of critical current density. Journal of Applied Physics, 114 (16), 163910-1-163910-9.Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density AbstractThe dependence of the critical current density ( J c ) on electric field criteria (E cr ) is studied for high-quality YBCO (YBa 2 Cu 3 O 7 ) thin films over the entire applied magnetic field (B a ) range. The quantitative model describing the J c (B a ) dependence is compared and explained for the critical current densities obtained by different measurement techniques. Transport current and quasi-equilibrium magnetization measurement data can successfully be fitted by the model with appropriate electric field criteria. The dependence of the irreversibility field on the E cr criterion can be obtained within the model. At the same time, the dynamic magnetization measurements of the J c (B a ) curves strongly depend on instrumentally defined parameters, introducing inconsistencies in the experimental results. Therefore, the model calculations are able to explain the J c (B a ) curves only if the instrumental vibrations affecting vortex behaviour are taken into account. However, the nature of the observed dependence on the vibration of the samples is unclear. Different frequencies of the sample vibrations have been investigated. It is revealed that if the frequency tends to zero, the J c (B a ) curves are well described by the model. We have outlined a number of possibilities which may be responsible for the behaviour observed. However, none of the existing theories can explain the effect of the vibrations, which exponentially degrade the irreversibility field to a certain tampered B irr value at frequencies larger than ≃25 Hz . Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density The dependence of the critical current density (J c ) on electric field criteria (E cr ) is studied for high-quality YBCO (YBa 2 Cu 3 O 7 ) thin films over the entire applied magnetic field (B a ) range. The quantitative model describing the J c ðB a Þ dependence is compared and explained for the critical current densities obtained by different measurement techniques. Transport current and quasi-equilibrium magnetization measurement data can successfully be fitted by the model with appropriate electric field criteria. The dependence of the irreversibility field on the E cr criterion can be obtained within the model. At the same time, the dynamic magnetization measurements of the J c ðB a Þ curves strongly depend on instrumentally defined parameters, introducing inconsistencies in the experimental results. Therefore, the model calculations are able to explain the J c ðB a Þ curves only if the instrumental vibrations affecting vortex behaviour are taken into account. However, the nature of the observed dependence on the vibration o...

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Section: J C (B a ) Model For Ybco Filmsmentioning

confidence: 99%

Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density

Golovchanskiy

Pan

Shcherbakova

et al. 2013

Journal of Applied Physics

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“…The sign is determined by the slope of the magnetic flux density in the cylinder. Equation (1) implies that, similar to the Kim model, the critical current density of the exponent model varies with the magnetic flux density as well.…”

Section: Formulationmentioning

confidence: 90%

“…With the development of large single grain superconductors with strong flux pinning, type II superconductors have been an interesting research subject over the past decade [1][2][3][4][5]. The high temperature superconductor, however, is susceptible to mechanical failure due to their brittleness and drawbacks [6].…”

Section: Introductionmentioning

confidence: 99%

Exponent model for stress distributions in a superconducting cylinder with a concentric elliptic hole

Feng

2013

JAE

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In this paper, the distributions of the stresses induced by flux pinning in a superconducting cylinder with a concentric elliptic hole are investigated. First, the distribution function of the flux density during field descent after field cooling process is given by adopting the exponent model for the critical current state. Then, the flux pinning forces are further derived. Finally, numerous numerical results are plotted by using finite element method and are analyzed in detail. Numerical results show that for the superconducting cylinder with an elliptic hole, along the direction of the long axis, the phenomenon of stress concentration for hoop stress occurs at the hole edge, and that in general, the radial stress changes rapidly near the hole edge. In addition, both the shape of the hole and the model parameter of the present critical state model have important and different effects on the stress distributions. Results presented in this paper should have potential applications to the design of superconducting materials.

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“…At the same time, at the low field region (self-field region), the 5 Hz film exhibits the most optimal properties at low temperatures. These differences are likely the ground for existing inconsistencies in determining the pinning mechanism in the PLD YBCO films, ranging from dislocation dominance 28,29,61,85 and twin boundaries 81 to small non-superconducting inclusions of Y 2 O 3 83,84 and even surface pinning 86 and Josephson-like weak-links 79 , which may simply represent different but limited aspects of the entire picture, as shown in this work.…”

Section: B Ybco Thin Filmsmentioning

confidence: 98%

“…The quantitative agreement between densities of dislocations and islands, as well as B * , J c (B a ) and J c (0) may be not easy to find 77 because while B * is determined by density of pinning centres in single vortex pinning regime, J c (0) is established by strength of individual pinning cites 28 . In addition, other effective pinning defects 77,78 , such as twin boundaries 26,81 , oxygen vacancies 82 and Y 2 O 3 inclusions 83,84 are present and can be affected by deposition frequency. Indeed, smoother transitions at the higher deposition frequencies from the plateau-like J c (B a ) dependence at B a → 0 to the powerlaw dependence at the larger fields [insert in Fig.…”

Section: B Ybco Thin Filmsmentioning

confidence: 99%

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

Golovchanskiy

Pan

Fedoseev

et al. 2014

Applied Surface Science

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The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behavior as a function of the applied magnetic field [ Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed. The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behaviour as a function of the applied magnetic field [Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed.

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Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Cited by 30 publications

References 34 publications

Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density

Rectifying differences in transport, dynamic, and quasi-equilibrium measurements of critical current density

Exponent model for stress distributions in a superconducting cylinder with a concentric elliptic hole

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

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