Magneto-optical observation of flux pinning at the grain boundary in a Bi2Sr2CaCu2O<i>x</i> superconductor

Nakamura, N.; Gu, G. D.; Takamuku, K.; Muarkami, M.; Koshizuka, N.

doi:10.1063/1.108004

Cited by 37 publications

(13 citation statements)

References 12 publications

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“…The T c values of individual crystals cut from the rod measured by low field ͑10 Oe͒ dc magnetization were approximately 87 K. The flux density distribution in the bc plane was observed by the high contrast magneto-optical flux imaging method ͑HICOM͒, 1 in which an iron garnet film is placed on the sample surface and the flux density distribution is visualized as a magnetic domain pattern of the garnet film by Faraday effect using a polarized microscope. The same phenomenon has been reported by Nakamura et al 4 On the other hand, in the case of zero field reduced after field cooling ͑FC͒ to 24 K in 850 Oe, white domains were observed in the same regions where maze domain patterns appeared in Fig. 1.…”

supporting

confidence: 87%

Magneto-optical and high resolution electron microscopy studies of flux pinning at grain boundaries in Bi2Sr2CaCu2Ox crystals

Egi

Wen

Kubota

et al. 1995

Applied Physics Letters

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We have studied the flux pinning behavior of Bi2Sr2CaCu2Ox multicrystalline samples using a magneto-optical flux observation method. When a magnetic field is applied parallel to the ab plane, we find low flux density regions at the intersections of small angle grain boundaries. The flux density distribution can be explained by considering both flux pinning at the small angle grain boundaries and the intrinsic pinning effect at the BiO layers. High resolution electron microscopy observations show that amorphous patches with columnar structure exist at the small angle grain boundaries (<20°), while other defects such as misfit dislocations and distorted microstructures appear at general grain boundaries. The fact that flux pinning only occurs at small angle grain boundaries (<20°) indicates that the columnar amorphous structures could act as flux pinning centers.

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confidence: 87%

Magneto-optical and high resolution electron microscopy studies of flux pinning at grain boundaries in Bi2Sr2CaCu2Ox crystals

Egi

Wen

Kubota

et al. 1995

Applied Physics Letters

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“…In polycrystalline samples, applied magnetic fields usually enter or leave the samples via the grain boundaries, preferably along those with large misorientation angles, as has been imaged directly in magneto-optical studies, an example of which is given by Fig. 50 (Forkl et al, 1990;Nakamura et al, 1992;Dorosinskii et al, 1993;Schuster et al, 1993;Koblischka et al, 1994;Turchinskaya et al, 1994;Vlasko-Vlasov et al, 1994;Polyanskii et al, 1996;Jooss et al, 1999;Albrecht et al, 2000aAlbrecht et al, , 2000bFeldmann et al, 2000;Jooss, Bringmann, et al, 2000;Kawano et al, 2000) and in scanning SQUID microscopy investigations (Tsai et al, 2001). With the field profile known, the supercurrent distributions can be derived by inversion techniques (Polyanskii et al, 1996;Jooss et al, 1999;Albrecht et al, 2000a;Kawano et al, 2000;Jooss, Albrecht, et al, 2001).…”

Section: J Penetration Of Magnetic Flux Into Grain Boundariesmentioning

confidence: 99%

Grain boundaries in high-Tcsuperconductors

2002

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Since the first days of high-T c superconductivity, the materials science and the physics of grain boundaries in superconducting compounds have developed into fascinating fields of research. Unique electronic properties, different from those of the grain boundaries in conventional metallic superconductors, have made grain boundaries formed by high-T c cuprates important tools for basic science. They are moreover a key issue for electronic and large-scale applications of high-T c superconductivity. The aim of this review is to give a summary of this broad and dynamic field. Starting with an introduction to grain boundaries and a discussion of the techniques established to prepare them individually and in a well-defined manner, the authors present their structure and transport properties. These provide the basis for a survey of the theoretical models developed to describe grain-boundary behavior. Following these discussions, the enormous impact of grain boundaries on fundamental studies is reviewed, as well as high-power and electronic device applications. CONTENTS I. Introduction 485 II. Introduction to Grain Boundaries 486 III. Preparation of Single Grain Boundaries 488 A. Bicrystalline junctions 489 B. Biepitaxial junctions 489 C. Step-edge junctions 491 IV. Structural Properties 491 V. Transport Properties of Grain Boundaries 496 A. Current-voltage characteristics 496 B. Critical current density 498 1. Dependence on grain-boundary angle 498 2. Temperature dependence of the critical currents 502 3. Magnetic-field dependence of the critical currents 502 C. Current-phase relation 504 D. Normal-state resistivity 504 E. The I c R n product 505 F. Grain-boundary capacitance 506 G. Microwave properties 507 H. Grain-boundary noise 507 I. Self-generated magnetic flux 509 J. Penetration of magnetic flux into grain boundaries 510 VI. Effects of Doping 510 VII. Grain-Boundary Mechanisms 511 A. Mechanisms based on structural properties 511 B. Mechanisms based on deviations from ideal stoichiometry 512 C. Order-parameter symmetry-based mechanisms 514 D. Interface charging and band bending 515 E. Mechanisms based on direct suppression of the pairing mechanism 516 VIII. Control of Grain Boundaries with Electric Fields or Quasiparticle Injection 517 A. Applied electric fields 517 B. Quasiparticle injection 518 IX. Irradiation of Grain Boundaries 518 A. Irradiation with electrons 518 B. Irradiation with light 518 C. Irradiation with ions 519 X. Bulk Applications 519 A. Powder-in-tube method 520 B. Coated conductors 520 XI. Applications of Grain Boundaries in Thin Films 522 A. SQUIDs 522 B. Radiation detectors and spectrometers 524 C. Three-terminal devices 525 D. Superconducting logic circuits 526 E. Research devices 526 XII. Summary and Outlook 528 Acknowledgments 529 References 529

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“…Within the same temperature range there occurs an essential increase in <E>, most likely connected with the increase in the amount of low-angle boundaries too. It is well known that lowangle boundaries can be strong pinning centers [8,40,41]. That is why the increase in J c and B irr is attributed not only to the decrease in the amount of weak links at intercolony boundaries, but also to an increase of the mean effective pinning energy.…”

Section: Superconducting Propertiesmentioning

confidence: 94%

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

Imayev

Daminov

Reissner

et al. 2007

Physica C: Superconductivity and its Applications

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Magneto-optical observation of flux pinning at the grain boundary in a Bi2Sr2CaCu2Ox superconductor

Cited by 37 publications

References 12 publications

Magneto-optical and high resolution electron microscopy studies of flux pinning at grain boundaries in Bi2Sr2CaCu2Ox crystals

Magneto-optical and high resolution electron microscopy studies of flux pinning at grain boundaries in Bi2Sr2CaCu2Ox crystals

Grain boundaries in high-Tcsuperconductors

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

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