Microwave absorption studies on high-T sub c superconductors and related materials IV ESR as a probe of flux pinning in Y-Ba-Cu-O superconductors prepared by the MPMG method

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Modern Physics Letters B; (Singapore)

DOI:https://doi.org/10.1142/S0217984991001222· OSTI ID:5162069

Sugawara, K; Baar, D J; Murakami, M; Kondoh, A; Shiohara, Y; Tanaka, S; Yamaguchi, K ^[1]

---

1. Superconductivity Research Lab., ISTEC, 10-13 Shinonome, 1-chome Koto-ku, Tokyo 135 (JP)

This paper reports that the electron spin resonances of both DPPH surface coatings and Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5} (211 phase) non-superconducting inclusions have been used to probe the flux pinning in high critical current density Y-Ba-Cu-O bulk superconductors prepared by the MPMG (Melt-Powder-Melt-Growth) method. The ESR lineshapes for both the surface coatings and the 211 inclusions were observed to broaden when the MPMG samples entered the superconducting state. The excess ESR linewidth for the DPPH coatings was found to increase monotonically with decreasing temperature, as the result of increasing field gradients due to pinned flux. The ESR linewidth of the 211 inclusions had a complicated temperature dependence. This linewidth was less than that of isolated Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5} below 20 K, possibly due to a lower magnetic ordering temperature, mechanical stress, and/or different composition of the inclusions as compared to isolated Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5}. Strong hysteresis in the ESR linewidths due to flux trapping was observed at low temperatures. Comparisons with the ESR linewidth of DPPH coated on the surface of the samples suggest that this flux trapping is due to strong pinning in the neighborhood of the 211 inclusions.

• OSTI ID: 5162069
• Journal Information: Modern Physics Letters B; (Singapore), Journal Name: Modern Physics Letters B; (Singapore) Vol. 5:14; ISSN MPLBE; ISSN 0217-9849
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
661200 -- Techniques of General Use in Physics-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
COATINGS
COPPER COMPOUNDS
CRITICAL CURRENT
CUPRATES
CURRENTS
DPPH
ELECTRIC CURRENTS
ELECTRON SPIN RESONANCE
HIGH-TC SUPERCONDUCTORS
LINE WIDTHS
MAGNETIC FLUX
MAGNETIC RESONANCE
MELTING
MICROWAVE SPECTRA
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
POWDERS
RADICALS
RESONANCE
SPECTRA
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS