Spin-polarons and high-{Tc} superconductivity
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).
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10158128
- Report Number(s):
- CONF-9404139-1; ON: DE94013273; TRN: 94:012163
- 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
Similar Records
Spin-polaron theory of high-{Tc} superconductivity: 2, electronic structure of the CuO{sub 2} planes
Spin-polaron theory of high-{Tc} superconductivity: 3, Gap function and critical temperature