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Title: Model of nuclear relaxation in YBa sub 2 Cu sub 3 O sub 7 minus. delta

Abstract

We examine nuclear spin-lattice relaxation rates (1/{ital T}{sub 1}) at copper (Cu), oxygen (O), and yttrium (Y) sites in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. We use a two-hole band model consisting of strongly Heisenberg superexchange coupled spins ({ital S}=1/2) on Cu sites that are exchange coupled with strength {ital J}{sub {ital p}{ital d}} to itinerant oxygen holes introduced by doping. The Cu(1) (chain) spins are modeled by one-dimensional Heisenberg chains; the Cu(2) (planar) spins are modeled by two-dimensional Schwinger boson mean-field theory. We first consider the limit of {ital J}{sub {ital p}{ital d}}=0 to explain the following: (i) qualitatively the superlinear behavior of 1/{ital T}{sub 1} versus temperature {ital T} on Cu(1) (chain sites) in terms of their quasi-one-dimensional character, (ii) the insufficiency of arguments producing a {ital T}{sup 1/2} temperature dependence on Cu(2) (planar) sites due to the vastly stronger temperature dependence of the antiferromagnetic fluctuations, (iii) the development of an anomaly in 1/{ital T}{sub 1}{ital T} similar to experimental data due to anisotropy and/or quantum disorder induced spin gaps,'' (iv) the need to produce some recalibration of estimates of transferred Cu(2) to Cu nuclear coupling with proper account of intersite fluctuations, and (v) the dramatic reduction of the transferredmore » Cu spin fluctuation contribution to 1/{ital T}{sub 1} on Y and O(2,3) (planar) sites arising from form-factor effects (and hence the observation of metallic Korringa behavior at these nuclei). Next, we demonstrate formally that for finite values of {ital J}{sub {ital p}{ital d}} the low-temperature proportionality of O(2,3) and Cu(2) rates may be understood as arising from coupling of Cu- and O-hole spin susceptibilities in the presence of a Cu(2) anisotropy or spin gap.« less

Authors:
;  [1]
  1. Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, Ohio 43210 (US)
Publication Date:
OSTI Identifier:
7155108
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (USA)
Additional Journal Information:
Journal Volume: 41:16; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BARIUM OXIDES; SPIN-LATTICE RELAXATION; COPPER OXIDES; YTTRIUM OXIDES; ANTIFERROMAGNETISM; BAND THEORY; BOSONS; EXCHANGE INTERACTIONS; FLUCTUATIONS; HEISENBERG MODEL; HOLES; NUCLEAR MAGNETIC RESONANCE; TYPE-II SUPERCONDUCTORS; ALKALINE EARTH METAL COMPOUNDS; BARIUM COMPOUNDS; CHALCOGENIDES; COPPER COMPOUNDS; CRYSTAL MODELS; INTERACTIONS; MAGNETIC RESONANCE; MAGNETISM; MATHEMATICAL MODELS; OXIDES; OXYGEN COMPOUNDS; RELAXATION; RESONANCE; SUPERCONDUCTORS; TRANSITION ELEMENT COMPOUNDS; VARIATIONS; YTTRIUM COMPOUNDS; 360204* - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Cox, D L, and Trees, B R. Model of nuclear relaxation in YBa sub 2 Cu sub 3 O sub 7 minus. delta. United States: N. p., 1990. Web. doi:10.1103/PhysRevB.41.11260.
Cox, D L, & Trees, B R. Model of nuclear relaxation in YBa sub 2 Cu sub 3 O sub 7 minus. delta. United States. https://doi.org/10.1103/PhysRevB.41.11260
Cox, D L, and Trees, B R. 1990. "Model of nuclear relaxation in YBa sub 2 Cu sub 3 O sub 7 minus. delta". United States. https://doi.org/10.1103/PhysRevB.41.11260.
@article{osti_7155108,
title = {Model of nuclear relaxation in YBa sub 2 Cu sub 3 O sub 7 minus. delta},
author = {Cox, D L and Trees, B R},
abstractNote = {We examine nuclear spin-lattice relaxation rates (1/{ital T}{sub 1}) at copper (Cu), oxygen (O), and yttrium (Y) sites in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. We use a two-hole band model consisting of strongly Heisenberg superexchange coupled spins ({ital S}=1/2) on Cu sites that are exchange coupled with strength {ital J}{sub {ital p}{ital d}} to itinerant oxygen holes introduced by doping. The Cu(1) (chain) spins are modeled by one-dimensional Heisenberg chains; the Cu(2) (planar) spins are modeled by two-dimensional Schwinger boson mean-field theory. We first consider the limit of {ital J}{sub {ital p}{ital d}}=0 to explain the following: (i) qualitatively the superlinear behavior of 1/{ital T}{sub 1} versus temperature {ital T} on Cu(1) (chain sites) in terms of their quasi-one-dimensional character, (ii) the insufficiency of arguments producing a {ital T}{sup 1/2} temperature dependence on Cu(2) (planar) sites due to the vastly stronger temperature dependence of the antiferromagnetic fluctuations, (iii) the development of an anomaly in 1/{ital T}{sub 1}{ital T} similar to experimental data due to anisotropy and/or quantum disorder induced spin gaps,'' (iv) the need to produce some recalibration of estimates of transferred Cu(2) to Cu nuclear coupling with proper account of intersite fluctuations, and (v) the dramatic reduction of the transferred Cu spin fluctuation contribution to 1/{ital T}{sub 1} on Y and O(2,3) (planar) sites arising from form-factor effects (and hence the observation of metallic Korringa behavior at these nuclei). Next, we demonstrate formally that for finite values of {ital J}{sub {ital p}{ital d}} the low-temperature proportionality of O(2,3) and Cu(2) rates may be understood as arising from coupling of Cu- and O-hole spin susceptibilities in the presence of a Cu(2) anisotropy or spin gap.},
doi = {10.1103/PhysRevB.41.11260},
url = {https://www.osti.gov/biblio/7155108}, journal = {Physical Review, B: Condensed Matter; (USA)},
issn = {0163-1829},
number = ,
volume = 41:16,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 1990},
month = {Fri Jun 01 00:00:00 EDT 1990}
}