Influence of field decrements on the relaxation behavior of thin high- T c superconductors measured using a levitation balance

Michael Rudolf Koblischka, Jerome Meiser, Uwe Hartmann

研究成果: Article

抄録

Conventional relaxation measurements on various samples (a YBa 2Cu 3O 7-δ thin film, a YBa 2Cu 3O 7-δ-coated conductor, and a Bi 2Sr 2Ca 2Cu 3O 10+δ tape) using a levitation balance are presented that are measured after a departure from the critical state by means of a small retraction Δ d of the permanent magnet, which corresponds to a small field reduction ΔH a. In the case of YBa 2Cu 3O 7-δ, flux creep rates S are found to decrease with increasing ΔH a until a small plateau is reached, where flux creep is effectively stopped. A further increase in Δ H a before the relaxation measurement leads to a change of sign of the creep rate. For the Bi 2Sr 2Ca 2Cu 3O 10+δ tape, only a continuous decrease in S is obtained. An explanation of this effect is given based on calculations of flux density profiles and critical current densities in perpendicular geometry. The differences to the Bean model (i.e., longitudinal geometry) are discussed.

元の言語English
記事番号6159060
ジャーナルIEEE Transactions on Applied Superconductivity
22
発行部数2
DOI
出版物ステータスPublished - 2012 4 1
外部発表Yes

Fingerprint

levitation
tapes
Superconducting materials
Creep
Fluxes
Tapes
geometry
permanent magnets
plateaus
critical current
Geometry
conductors
flux density
current density
Permanent magnets
thin films
profiles
Thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

これを引用

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abstract = "Conventional relaxation measurements on various samples (a YBa 2Cu 3O 7-δ thin film, a YBa 2Cu 3O 7-δ-coated conductor, and a Bi 2Sr 2Ca 2Cu 3O 10+δ tape) using a levitation balance are presented that are measured after a departure from the critical state by means of a small retraction Δ d of the permanent magnet, which corresponds to a small field reduction ΔH a. In the case of YBa 2Cu 3O 7-δ, flux creep rates S are found to decrease with increasing ΔH a until a small plateau is reached, where flux creep is effectively stopped. A further increase in Δ H a before the relaxation measurement leads to a change of sign of the creep rate. For the Bi 2Sr 2Ca 2Cu 3O 10+δ tape, only a continuous decrease in S is obtained. An explanation of this effect is given based on calculations of flux density profiles and critical current densities in perpendicular geometry. The differences to the Bean model (i.e., longitudinal geometry) are discussed.",
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AU - Meiser, Jerome

AU - Hartmann, Uwe

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N2 - Conventional relaxation measurements on various samples (a YBa 2Cu 3O 7-δ thin film, a YBa 2Cu 3O 7-δ-coated conductor, and a Bi 2Sr 2Ca 2Cu 3O 10+δ tape) using a levitation balance are presented that are measured after a departure from the critical state by means of a small retraction Δ d of the permanent magnet, which corresponds to a small field reduction ΔH a. In the case of YBa 2Cu 3O 7-δ, flux creep rates S are found to decrease with increasing ΔH a until a small plateau is reached, where flux creep is effectively stopped. A further increase in Δ H a before the relaxation measurement leads to a change of sign of the creep rate. For the Bi 2Sr 2Ca 2Cu 3O 10+δ tape, only a continuous decrease in S is obtained. An explanation of this effect is given based on calculations of flux density profiles and critical current densities in perpendicular geometry. The differences to the Bean model (i.e., longitudinal geometry) are discussed.

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