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Title: Frustrated phase separation and high temperature superconductivity

Abstract

A dilute system of neutral holes in an antiferromagnet separates into a hole-rich and a hole-poor phase. The phase separation is frustrated by long-range Coulomb interactions but, provided the dielectric constant is sufficiently large, there remain large-amplitude low-energy fluctuations in the hole density at intermediate length scales. The extensive experimental evidence showing that this behavior giver, a reasonable picture of high temperature superconductors is surveyed. Further, it is shown that the scattering of mobile holes from the local density fluctuations may account for the anomalous normal-state properties of high temperature superconductors and also provide the mechanism of pairing.

Authors:
 [1];  [2]
  1. (Brookhaven National Lab., Upton, NY (United States))
  2. (California Univ., Los Angeles, CA (United States). Dept. of Physics)
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
7293457
Report Number(s):
BNL-47796; CONF-9205236-1
ON: DE92019249
DOE Contract Number:
AC02-76CH00016
Resource Type:
Conference
Resource Relation:
Conference: Conference on phase separation in cuprate superconductors, Sicily (Italy), 6-12 May 1992
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HIGH-TC SUPERCONDUCTORS; SUPERCONDUCTIVITY; ABSORPTION SPECTROSCOPY; ANTIFERROMAGNETIC MATERIALS; BARIUM OXIDES; CUPRATES; MAGNETIC PROPERTIES; PHASE STUDIES; YTTRIUM OXIDES; ALKALINE EARTH METAL COMPOUNDS; BARIUM COMPOUNDS; CHALCOGENIDES; COPPER COMPOUNDS; ELECTRIC CONDUCTIVITY; ELECTRICAL PROPERTIES; MAGNETIC MATERIALS; MATERIALS; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SPECTROSCOPY; SUPERCONDUCTORS; TRANSITION ELEMENT COMPOUNDS; YTTRIUM COMPOUNDS; 360204* - Ceramics, Cermets, & Refractories- Physical Properties; 360207 - Ceramics, Cermets, & Refractories- Superconducting Properties- (1992-); 665411 - Basic Superconductivity Studies- (1992-)

Citation Formats

Emery, V.J., and Kivelson, S.A.. Frustrated phase separation and high temperature superconductivity. United States: N. p., 1992. Web.
Emery, V.J., & Kivelson, S.A.. Frustrated phase separation and high temperature superconductivity. United States.
Emery, V.J., and Kivelson, S.A.. 1992. "Frustrated phase separation and high temperature superconductivity". United States. doi:. https://www.osti.gov/servlets/purl/7293457.
@article{osti_7293457,
title = {Frustrated phase separation and high temperature superconductivity},
author = {Emery, V.J. and Kivelson, S.A.},
abstractNote = {A dilute system of neutral holes in an antiferromagnet separates into a hole-rich and a hole-poor phase. The phase separation is frustrated by long-range Coulomb interactions but, provided the dielectric constant is sufficiently large, there remain large-amplitude low-energy fluctuations in the hole density at intermediate length scales. The extensive experimental evidence showing that this behavior giver, a reasonable picture of high temperature superconductors is surveyed. Further, it is shown that the scattering of mobile holes from the local density fluctuations may account for the anomalous normal-state properties of high temperature superconductors and also provide the mechanism of pairing.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1992,
month = 1
}

Conference:
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  • A dilute system of neutral holes in an antiferromagnet separates into a hole-rich and a hole-poor phase. The phase separation is frustrated by long-range Coulomb interactions but, provided the dielectric constant is sufficiently large, there remain large-amplitude low-energy fluctuations in the hole density at intermediate length scales. The extensive experimental evidence showing that this behavior giver, a reasonable picture of high temperature superconductors is surveyed. Further, it is shown that the scattering of mobile holes from the local density fluctuations may account for the anomalous normal-state properties of high temperature superconductors and also provide the mechanism of pairing.
  • The authors review the extensive evidence from model calculations that neutral holes in an antiferromagnet separate into hole-rich and hole-poor phases. All known solvable limits of models of holes in a Heisenberg antiferromagnet exhibit this behavior. They show that when the phase separation is frustrated by the introduction of long-range Coulomb interactions, the typical consequence is either a modulated (charge density wave) state or a superconducting phase. They then review some of the strong experimental evidence supporting an electronically-driven phase separation of the holes in the cuprate superconductors and the related Ni oxides. Finally they argue that frustrated phase separationmore » in these materials can account for many of the anomalous normal state properties of the high temperature superconductors and provide the mechanism of superconductivity. In particular, they show that the T-linear resistivity of the normal state is a paraconductivity associated with a novel composite pairing, although the ordered superconducting state is more conventional.« less
  • The authors review the extensive evidence from model calculations that neutral holes in an antiferromagnet separate into hole-rich and hole-poor phases. All known solvable limits of models of holes in a Heisenberg antiferromagnet exhibit this behavior. The authors show that when the phase separation is frustrated by the introduction of long-range Coulomb interactions, the typical consequence is either a modulated (charge density wave) state or a superconducting phase. The authors then review some of the strong experimental evidence supporting an electronically-driven phase separation of the holes in the cuprate superconductors and the related Ni oxides. Finally, the authors argue thatmore » frustrated phase separation in these materials can account for many of the anomalous normal state properties of the high temperature superconductors and provide the mechanism of superconductivity. In particular, it is shown that the T-linear resistivity of the normal state is a paraconductivity associated with a novel composite pairing, although the ordered superconducting state is more conventional.« less
  • La[sub 2-x]Sr[sub x]CuO[sub 4+[delta]] with x = 0.01, 0.025, 0.050, 0.10 and 0.16 and excess oxygen [delta] incorporated by high-pressure O[sub 2] anneals. These compounds were examined using time-of-flight neutron diffraction data. Various models were fit by Rietveld least-squares refinement, with the maximum amount of [delta] being only of the order of 10 standard deviations. [delta] is largest for x near 0, is zero for x = 0.10 and is intermediate for x = 0.16. Only the sample with x = 0.01 is found to phase separate distinctly into a nearly stoichiometric phase with [delta] [approx] 0 and an oxygen-richmore » superconducting phase as the temperature is lowered. Coincidence of phase separation and Neel temperature strongly suggests that the phase separation is driven by free energy provided by long-range antiferromagnetic ordering in the nearly stoichiometric, weakly Sr-doped La[sub 2-x]Sr[sub x]CuO[sub 4]. The excess oxygen stoichiometry shows that at low values of x, hole doping is provided primarily by the excess oxygen, and is enhanced substantially by phase separation. At larger values of x, excess oxygen is no longer incorporated, and hole doping is provided by the substitution of Sr[sup +2] for La[sup +3].« less
  • The structural, superconducting and normal-state properties of La{sub 2}MO{sub 4+{delta}} (M = Cu, Ni, Co) were studied by neutron powder diffraction, thermogravimetric analysis and resistivity measurements. La{sub 2}CuO{sub 4+{delta}} was found to undergo phase separation near room temperature into antiferromagnetic La{sub 2}CuO{sub 4} and superconducting La{sub 2}CuO{sub 4.08}. Single-phase, metallic, superconducting La{sub 2}CuO{sub 4.08} was prepared under 25 kbar of O{sub 2} at 500{degree}C. The excess oxygen present as O{sup =} ions provides a doping mechanism analogous to alkaline-earth metal ion substitution. La{sub 2}NiO{sub 4+{delta}} and La{sub 2}CoO{sub 4+{delta}} undergo a similar phase separation for 0.02<{delta}<0.12 and 0<{delta}<0.16, respectively. Themore » structure of the interstitial excess oxygen defect was determined for a single-phase La{sub 2}NiO{sub 4.18} sample. A different excess oxygen defect forms for material with 0{le}{delta}{le}0.02. All stoichiometric ({delta}=0) compounds have the same Cmca orthorhombic structure and are semiconducting and antiferromagnetic. 17 refs., 6 figs.« less