Formation of the low-field peak in magnetization loops of high-Tc superconductors

Michael Rudolf Koblischka, L. Půst, M. Jirsa, T. H. Johansen

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The positions of the central (low-field) peak in the magnetization hysteresis loops (MHLs) are analyzed in various high-Tc superconducting samples comprising several RBa2Cu3O7-δ (RBCO; R = rare earths) single crystals of different thicknesses, a laser-ablated YBa2Cu3O7-δ (YBCO) thin film, Ag-sheathed (Pb,Bi)2Sr2Ba2Cu3O10+δ (Bi-2223) mono- and multifilamentary tapes, and a model sample designed to reproduce a layer of grains [M.R. Koblischka et al., Appl. Phys. Lett. 70 (1997) 514]. The single crystals and the thin film show the peak at zero-field or at negative applied fields on the descending field branch according to the critical state models, the Bi-2223 tapes are found to exhibit the peak anomalously in positive applied fields. In order to better understand the magnetization processes leading to the formation of the central peak in the MHLs, the local field distributions in applied fields close to zero were studied using magneto-optic (MO) flux visualization on the same samples. These flux patterns show how the vortices are rearranged when sweeping through zero-field. A large demagnetizing effect ('perpendicular geometry') facilitates the penetration of vortices of opposite polarity, especially along structural defects, thus, forcing the central peak towards zero or even to very small positive fields. To explain the anomalous behaviour found in Bi-2223 tapes, effects of granularity have to be considered additionally. Further, we discuss the interaction of the central peak with other 'peak effects' observed in MHLs.

Original languageEnglish
Pages (from-to)101-114
Number of pages14
JournalPhysica C: Superconductivity and its Applications
Volume320
Issue number1
DOIs
Publication statusPublished - 1999 Jul 1
Externally publishedYes

Fingerprint

Superconducting materials
Magnetization
Hysteresis loops
Tapes
magnetization
Vortex flow
tapes
Single crystals
Fluxes
hysteresis
Thin films
Magnetooptical effects
Rare earths
vortices
Visualization
single crystals
magneto-optics
Defects
thin films
Geometry

ASJC Scopus subject areas

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

Cite this

Formation of the low-field peak in magnetization loops of high-Tc superconductors. / Koblischka, Michael Rudolf; Půst, L.; Jirsa, M.; Johansen, T. H.

In: Physica C: Superconductivity and its Applications, Vol. 320, No. 1, 01.07.1999, p. 101-114.

Research output: Contribution to journalArticle

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