EPR study of polycrystalline superconductors with YBa sub 2 Cu sub 3 O sub 7 structure

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Journal of Low Temperature Physics; (USA)

DOI:https://doi.org/10.1007/BF00681880· OSTI ID:6193315

Alekseevskii, N E; Mitin, A V; Nizhankovskii, V I ^[1]; Garifullin, I A; Garif'yanov, N N; Khaliullin, G G ^[2]; Khylbov, E P ^[3]; Kochelaev, B I; Tagirov, L R ^[4]

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1. Institute for Physical Problems, Moscow (USSR)
2. Physicotechnical Institute, Kazan (USSR)
3. Institute for High Pressure Physics, Troitsk (USSR)
4. Kazan State Univ. (USSR)

Electron paramagnetic resonance (EPR) of Gd{sup 3+}, Eu{sup 2+}, and copper ions has been investigated in the high-{Tc} superconductor with YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} structure. It has been established that the system is heterogeneous at 0.15 {le} {delta} {le} 0.5 and consists of metallic and dielectric regions. The former arises due to oxygen enrichment while the later due to oxygen deficiency. The integral of exchange interaction between Gd{sup 3+} localized moments and conduction electrons J{sub sf} = 0.016 eV has been determined from the normal state temperature dependence of Gd{sup 3+} EPR linewidth for metallic regions. {Tc} depression by gadolinium-localized moments for GdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} was estimated to be {Delta}{Tc} {approx equal} {minus}2 K. Anomalies in linewidth temperature dependence upon transition from the normal to the superconducting state have given information about the value and temperature behavior of the superconductor's energy gap. The model, which gives the opportunity to understand some peculiarities of the EPR signal for YBa{sub 2}Cu{sub 3}O{sub {minus}{delta}} samples, is proposed in terms of several bottlenecked spin-subsystems: spin-liquid in CuO planes and Cu{sup 2+}-O{sup {minus}} and Cu{sup 2+}-O{sup 2{minus}} fragments in CuO chains.

• OSTI ID: 6193315
• Journal Information: Journal of Low Temperature Physics; (USA), Journal Name: Journal of Low Temperature Physics; (USA) Vol. 77:1-2; ISSN 0022-2291; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656002 -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ANGULAR MOMENTUM
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL FIELD
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
ENERGY GAP
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
LINE WIDTHS
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIC RESONANCE
MAGNETIC SUSCEPTIBILITY
MATHEMATICAL MODELS
ORTHORHOMBIC LATTICES
OXIDES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
POLYCRYSTALS
RARE EARTH COMPOUNDS
RELAXATION
RESONANCE
SPIN
SPIN-SPIN RELAXATION
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
VALENCE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES