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Title: Spin-polarons and high-{Tc} superconductivity

Abstract

The spin-polaron concept is introduced in analogy to ionic and electronic polarons and the assumptions underlying the author`s approach to spin-polaron mediated high-{Tc} superconductivity are discussed. Elementary considerations about the spin-polaron formation energy are reviewed and the possible origin of the pairing mechanism illustrated schematically. The electronic structure of the CuO{sub 2} planes is treated from the standpoint of antiferromagnetic band calculations that lead directly to the picture of holes predominantly on the oxygen sublattice in a Mott-Hubbard/charge transfer insulator. Assuming the holes to be described in a Bloch representation but with the effective mass renormalized by spin-polaron formation, equations for the superconducting gap, {Delta}, and transition temperature, {Tc}, are developed and the symmetry of {Delta} discussed. After further simplifications, {Tc} is calculated as a function of the carrier concentration, x. It is shown that the calculated behavior of {Tc}(x) follows the experimental results closely and leads to a natural explanation of the effects of under- and over-doping. The paper concludes with a few remarks about the evidence for the carriers being fermions (polarons) or bosons (bipolarons).

Authors:
Publication Date:
Research Org.:
Oak Ridge National Lab., TN (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10158128
Report Number(s):
CONF-9404139-1
ON: DE94013273; TRN: 94:012163
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Technical Report
Resource Relation:
Conference: Workshop on polarons and bipolarons in high Tc superconductors,Cambridge (United Kingdom),7-9 Apr 1994; Other Information: PBD: Mar 1994
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HIGH-TC SUPERCONDUCTORS; MATHEMATICAL MODELS; POLARONS; CARRIER DENSITY; FERMIONS; CHARGE CARRIERS; BOSONS; COPPER OXIDES; FERMI LEVEL; THEORETICAL DATA; EQUATIONS; 665411; BASIC SUPERCONDUCTIVITY STUDIES

Citation Formats

Wood, R F. Spin-polarons and high-{Tc} superconductivity. United States: N. p., 1994. Web. doi:10.2172/10158128.
Wood, R F. Spin-polarons and high-{Tc} superconductivity. United States. https://doi.org/10.2172/10158128
Wood, R F. Tue . "Spin-polarons and high-{Tc} superconductivity". United States. https://doi.org/10.2172/10158128. https://www.osti.gov/servlets/purl/10158128.
@article{osti_10158128,
title = {Spin-polarons and high-{Tc} superconductivity},
author = {Wood, R F},
abstractNote = {The spin-polaron concept is introduced in analogy to ionic and electronic polarons and the assumptions underlying the author`s approach to spin-polaron mediated high-{Tc} superconductivity are discussed. Elementary considerations about the spin-polaron formation energy are reviewed and the possible origin of the pairing mechanism illustrated schematically. The electronic structure of the CuO{sub 2} planes is treated from the standpoint of antiferromagnetic band calculations that lead directly to the picture of holes predominantly on the oxygen sublattice in a Mott-Hubbard/charge transfer insulator. Assuming the holes to be described in a Bloch representation but with the effective mass renormalized by spin-polaron formation, equations for the superconducting gap, {Delta}, and transition temperature, {Tc}, are developed and the symmetry of {Delta} discussed. After further simplifications, {Tc} is calculated as a function of the carrier concentration, x. It is shown that the calculated behavior of {Tc}(x) follows the experimental results closely and leads to a natural explanation of the effects of under- and over-doping. The paper concludes with a few remarks about the evidence for the carriers being fermions (polarons) or bosons (bipolarons).},
doi = {10.2172/10158128},
url = {https://www.osti.gov/biblio/10158128}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1994},
month = {3}
}