# 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}

}