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Proceedings Paper

Energy scale in determining Tc of cuprate superconductors
Author(s): Migaku Oda; Naoki Momono; Masayuki Ido
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Paper Abstract

In La2-xSrxCuO4(La214) and Bi2Sr2CaCu2O8+(delta ) (Bi2212), scanning tunneling spectroscopy (STS), break-junction tunneling spectroscopy (BJTS) and Raman scattering spectroscopy demonstrate that the superconducting-state energy gap (Delta) o at T << Tc increases monotonically with the lowering of hole-doping level p even below the optimal doping po, where Tc begins to decrease. On the basis of electronic specific heat, magnetic susceptibility, resistivity and STS data in La214, it is suggested that a pseudogap of almost the same energy scale as (Delta) o, a small energy scale pseudogap (SPG), will develop progressively below a certain temperature T* in La214 as in Bi2212. In the two systems, the size of SPG ((Delta) PGS), comparable to (Delta) o, essentially scales with SPG temperature T*; (Delta) PGS approximately (Delta) o approximately (2.3 +/- 0.3)kBT*. We also report the relation among (Delta) o, higher crossover temperature Tmax (> T*) and the corresponding large energy scale pseudogap (LPG) (Delta) PGL; (Delta) PGL approximately 3kBTmax approximately (alpha) (Delta) o ((alpha) equals 3 to 4 for Bi2212 and (alpha) equals 6 - 8 for La214). Furthermore, we report that Tc almost scales with p(Delta) o over a wide p range, except for high doping levels (p/po approximately> 1.3), where Tc is very close to the BCS expectation (Tc equals 2(Delta) o/4.3kB). We discuss some scenarios for the superconducting transition, where the energy scale in determining Tc is expected to be of order p(Delta) o.

Paper Details

Date Published: 6 September 2000
PDF: 12 pages
Proc. SPIE 4058, Superconducting and Related Oxides: Physics and Nanoengineering IV, (6 September 2000); doi: 10.1117/12.397853
Show Author Affiliations
Migaku Oda, Hokkaido Univ. (Japan)
Naoki Momono, Hokkaido Univ. (Japan)
Masayuki Ido, Hokkaido Univ. (Japan)

Published in SPIE Proceedings Vol. 4058:
Superconducting and Related Oxides: Physics and Nanoengineering IV
Davor Pavuna; Ivan Bozovic, Editor(s)

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