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Proceedings Paper

Tunneling studies on the energy gap evolution of Bi2Sr2CaCu2O8+8
Author(s): Migaku Oda; Naoki Momono; Masayuki Ido
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Paper Abstract

We report, on the basis of our recent tunneling experiments over wide temperatures (T) and hole-doping (p) ranges in Bi2212/vaccum/Bi2212 junctions fabricated using STM, that in the electronic excitation spectrum, there exists two kinds of pseudogaps (LPG and SPG) with different characteristic energies. The LPG, which is 3 to 4 times larger than the superconducting (SC) gap magnitude 2Δ0 develops below ~Tmax, where the magnetic susceptibility starts to decrease because of the gradual development of antiferromagnetic spin fluctuations. On the other hand, the SPG, whose magnitude is comparable to 2Δ0, develops progressively, in addition to the LPG, below the mean-field characteristic temperature Tco for d-wave superconductors, and then evolves into the SC-gap below Tc,suggesting that it will be some kind of precursor of superconditivity. Furthermore, in accordance with the SC transition, the high-energy feature of quasiparticle spectrum outside the SC-gap, changes from a broad hump to a clear dip and hump accompanied by a shift of the hump position toward lower energies, in addition to the rapid growth of SC-gap from SPG. We also report that Tc nearly scales with the product of Δ0 and p, kBTc~pΔ0' the effective SC gap is ~pΔ0 in high Tc cuprates, instead of Δ0 in conventional BCS superconductors.

Paper Details

Date Published: 7 November 2002
PDF: 11 pages
Proc. SPIE 4811, Superconducting and Related Oxides: Physics and Nanoengineering V, (7 November 2002); doi: 10.1117/12.452268
Show Author Affiliations
Migaku Oda, Hokkaido Univ. (Japan)
Naoki Momono, Hokkaido Univ. (Japan)
Masayuki Ido, Hokkaido Univ. (Japan)

Published in SPIE Proceedings Vol. 4811:
Superconducting and Related Oxides: Physics and Nanoengineering V
Ivan Bozovic; Davor Pavuna, Editor(s)

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