Theory of high temperature superconductivity in cuprates. 5: Mechanism of superconductivity

Journal Article · Tue Dec 30 04:00:00 EST 1997 · International Journal of Modern Physics B

DOI:https://doi.org/10.1142/S0217979297001957· OSTI ID:585912

Matsuno, Shunichi ^[1]; Ushio, Hideki ^[2]; Suwa, Yuji; Kamimura, Hiroshi ^[3]

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1. Univ. of Tokyo (Japan). Dept. of Physics
2. Tokyo National College of Technology (Japan)
3. Science Univ. of Tokyo (Japan). Dept. of Applied Physics

A possibility of phonon-mediated interaction as a mechanism of high-{Tc} superconductivity is discussed. Because of different spatial distribution of Bloch wave function for up-spin particle and down-spin particle in the present model, the effective pair interaction which is derived from electron-phonon interaction is shown to have significant momentum-transfer dependence that is quite different from ordinary phonon-mediated interaction. This characteristic of pair interaction together with the geometric feature of Fermi-surface derived in a previous paper 3 leads to a d{sub x{sup 2}{minus}y{sup 2}} symmetric gap state which is consistent with experimental results. Since d-wave state has much smaller Coulomb repulsion terms than s-wave state, strong electron-phonon coupling in the present model is expected to cause the occurrence of high-temperature superconductivity. However, in the present model, it is shown that a factor that reduces superconducting transition temperature appear as a result of a fluctuation effect of antiferromagnetic (AF) order of localized Cu spins. The factor {lambda}{sub s} which should be proportional to AF correlation length {lambda}{sub AF}, determines the time scale {tau}{sub s} which eliminates the contribution from the retarded effective pair interaction of time argument larger than {tau}{sub s}. Existence of length scale {lambda}{sub s} explains why {Tc} goes to zero as increasing hole carrier to some extent, and why nonmagnetic impurity such as Pb reduces {Tc} strongly. {lambda}{sub 2} also explains the finite density of zero-gap states observed in overdoped regime or samples with non-magnetic impurities.

• OSTI ID: 585912
• Journal Information: International Journal of Modern Physics B, Journal Name: International Journal of Modern Physics B Journal Issue: 32 Vol. 11; ISSN IJPBEV; ISSN 0217-9792
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
COPPER OXIDES
D WAVES
ELECTRON-PHONON COUPLING
FERMI LEVEL
HIGH-TC SUPERCONDUCTORS
MATHEMATICAL MODELS
SUPERCONDUCTIVITY
TRANSITION TEMPERATURE