Flux line lattice structure and behavior in antiphase boundary free vicinal YBa2Cu3O7−δ thin films

Durrell, John; Mennema, S. H.; Jooß, Ch.; Gibson, Gary A. P.; Barber, Z. H.; Zandbergen, H.W.; Evetts, J. E.

doi:10.1063/1.1576298

Cited by 11 publications

(10 citation statements)

References 18 publications

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“…Such defects will suppress in-plane vortex channeling. 30 Similar data sets were also obtained on 2°and 4°vicinal films. j c ͑͒ data obtained on 4°films is shown in Fig.…”

Section: Resultssupporting

confidence: 58%

“…This channeling effect will therefore be seen in any YBCO sample where the current is not directed along the a-b planes and the crystal structure is free of defects that disrupt the continuity of the a-b planes. 30 The channeling effect extends over a range of miscut angles, the upper limit being due to the difficulty of getting epitaxial growth on substrates with a large angle of miscut. As previously observed, channeling is suppressed at high temperatures irrespective of the miscut angle.…”

Section: Resultsmentioning

confidence: 99%

“…In the reduced symmetry found in measurements on vicinal films the expected intrinsic vortex channelling effect is observed. 29,30 As predicted from Eq. (2) the width of the vortex channeling effect has been shown to vary with changing superconducting anisotropy in calcium doped and deoxygenated YBCO films.…”

Section: Theorymentioning

confidence: 86%

“…[32][33][34][35][36] It should be noted that the films had a low density of antiphase boundaries and stacking faults, this was confirmed by highresolution electron microscope studies. 30 These types of defects disrupt the a-b planes and make the interpretation of observed critical current in terms of the flux line lattice structure and anisotropy impossible. Such defects, when present, do, however, strongly increase the observed critical current.…”

Section: Experimental Techniquementioning

confidence: 99%

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Critical currents in vicinalYBa2Cu3O7−δfilms

et al. 2004

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Most measurements of critical current densities in YBa 2 Cu 3 O 7−␦ thin films to date have been performed on films where the c axis is grown normal to the film surface. With such films, the analysis of the dependence of the critical current, j c , on the magnetic field angle is complex. The effects of extrinsic contributions to the angular field dependence of j c , such as the measurement geometry and disposition of pinning centers, are convoluted with those intrinsically due to the anisotropy of the material. As a consequence of this, it is difficult to distinguish between proposed flux line lattice structure models on the basis of angular critical current density measurements on c-axis films. Films grown on miscut (vicinal) substrates have a reduced measurement symmetry and thus provide a greater insight into the critical current anisotropy. In this paper previous descriptions of the magnetic field angle dependence of j c in YBa 2 Cu 3 O 7−␦ are reviewed. Measurements on YBa 2 Cu 3 O 7−␦ thin films grown on a range of vicinal substrates are presented and the results interpreted in terms of the structure and dimensionality of the flux line lattice in YBa 2 Cu 3 O 7−␦ . There is strong evidence for a transition in the structure of the flux line lattice depending on magnetic field magnitude, orientation, and temperature. As a consequence, a simple scaling law cannot, by itself, describe the observed critical current anisotropy in YBa 2 Cu 3 O 7−␦ . The experimentally obtained j c ͑͒ behavior of YBa 2 Cu 3 O 7−␦ is successfully described in terms of a kinked vortex structure for fields applied near parallel to the a-b planes.

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“…Such defects will suppress in-plane vortex channeling. 30 Similar data sets were also obtained on 2°and 4°vicinal films. j c ͑͒ data obtained on 4°films is shown in Fig.…”

Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Theorymentioning

confidence: 86%

Section: Experimental Techniquementioning

confidence: 99%

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Critical currents in vicinalYBa2Cu3O7−δfilms

et al. 2004

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“…In cuprates, for instance, the critical current density in the c crystallographic axis is much smaller than in the ab plane. There is also important anisotropy in REBCO vicinal films due to flux channeling [23,24].The "de-pinning" anisotropy of J c is due to anisotropic maximum pinning forces caused by either anisotropic pinning centres or anisotropic vortex cores [25]. When the current density J is perpendicular to B and the electric field E is parallel to J, the anisotropy of J c is always due to de-pinning anisotropy.…”

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confidence: 99%

3D modelling of macroscopic force-free effects in superconducting thin films and rectangular prisms

Kapolka¹,

Pardo²

2019

Supercond. Sci. Technol.

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When the magnetic field has a parallel component to the current density J there appear force-free effects due to flux cutting and crossing. This results in an anisotropic E(J) relation, being E the electric field. Understanding force-free effects is interesting not only for the design of superconducting power and magnet applications but also for material characterization.This work develops and applies a fast and accurate computer modeling method based on a variational approach that can handle force-free anisotropic E(J) relations and perform fully three dimensional (3D) calculations. We present a systematic study of force-free effects in rectangular thin films and prisms with several finite thicknesses under applied magnetic fields with arbitrary angle θ with the surface. The results are compared with the same situation with isotropic E(J) relation.The thin film situation shows gradual critical current density penetration and a general increase of the magnitude of the magnetization with the angle θ but a minimum at the remnant state of the magnetization loop. The prism model presents current paths with 3D bending for all angles θ. The average current density over the thickness agrees very well with the thin film model except for the highest angles.The prism hysteresis loops reveal a peak after the remnant state, which is due to the parallel component of the self-magnetic-field and is implicitly neglected for thin films.The presented numerical method shows the capability to take force-free situations into account for general 3D situations with a high number of degrees of freedom.The results reveal new features of force-free effects in thin films and prisms.Type II superconductors are essential for large bore or high-field magnets [1][2][3][4] and are promising for power applications, such as motors for air-plane [5,6] or ship propulsion [7,8], generators [9][10][11], grid power-transmission cables [12,13], transformers [14][15][16][17], and or fault-current limiters [18][19][20][21][22]. The Critical Current Density, J c , of type II superconductors depends on the magnitude and angle of the local magnetic field. There are three types of anisotropy which we call "intrinsic", "de-pinning", and "force free" anisotropy.The "intrinsic" anisotopy is the following. Certain superconductors present an axis with suppressed superconductivity, where the critical current density is lower. In cuprates, for instance, the critical current density in the c crystallographic axis is much smaller than in the ab plane. There is also important anisotropy in REBCO vicinal films due to flux channeling [23,24].The "de-pinning" anisotropy of J c is due to anisotropic maximum pinning forces caused by either anisotropic pinning centres or anisotropic vortex cores [25]. When the current density J is perpendicular to B and the electric field E is parallel to J, the anisotropy of J c is always due to de-pinning anisotropy. This kind of anisotropy is important for High-Temperature Superconductors (HTS), such as (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 and ...

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High velocity vortex channeling in vicinal YBCO thin films

Puica

Lang

Durrell

2012

Physica C: Superconductivity

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We report on electrical transport measurements at high current densities on optimally doped YBa2Cu3O7−δ thin films grown on vicinal SrTiO3 substrates. Data were collected by using a pulsed-current technique in a four-probe arrangement, allowing to extend the current–voltage characteristics to high supercritical current densities (up to 24 MA cm−2) and high electric fields (more than 20 V/cm), in the superconducting state at temperatures between 30 and 80 K. The electric measurements were performed on tracks perpendicular to the vicinal step direction, such that the current crossed between ab planes, under magnetic field rotated in the plane defined by the crystallographic c axis and the current density. At magnetic field orientation parallel to the cuprate layers, evidence for the sliding motion along the ab planes (vortex channeling) was found. The signature of vortex channeling appeared to get enhanced with increasing electric field, due to the peculiar depinning features in the kinked vortex range. They give rise to a current–voltage characteristics steeper than in the more off-plane rectilinear vortex orientations, in the electric field range below approximately 1 V/cm. Roughly above this value, the high vortex channeling velocities (up to 8.6 km/s) could be ascribed to the flux flow, although the signature of ohmic transport appeared to be altered by unavoidable macroscopic self-heating and hot-electron-like effects.

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Flux line lattice structure and behavior in antiphase boundary free vicinal YBa2Cu3O7−δ thin films

Abstract: Field angle dependent critical current, magneto-optical microscopy, and high resolution electron microscopy studies have been performed on

Cited by 11 publications

References 18 publications

Critical currents in vicinalYBa2Cu3O7−δfilms

Critical currents in vicinalYBa2Cu3O7−δfilms

3D modelling of macroscopic force-free effects in superconducting thin films and rectangular prisms

High velocity vortex channeling in vicinal YBCO thin films

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