Energy scale in determining Tc of cuprate superconductors

Migaku Oda; Naoki Momono; Masayuki Ido

doi:10.1117/12.397853

6 September 2000 Energy scale in determining T_c of cuprate superconductors

Migaku Oda, Naoki Momono, Masayuki Ido

Proceedings Volume 4058, Superconducting and Related Oxides: Physics and Nanoengineering IV; (2000) https://doi.org/10.1117/12.397853
Event: AeroSense 2000, 2000, Orlando, FL, United States

Abstract

In La_2-xSr_xCuO₄(La214) and Bi₂Sr₂CaCu₂O_8+(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 << T_c increases monotonically with the lowering of hole-doping level p even below the optimal doping p_o, where T_c 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) _PG^S), comparable to (Delta) _o, essentially scales with SPG temperature T*; (Delta) _PG^S approximately (Delta) _o approximately (2.3 +/- 0.3)k_BT*. We also report the relation among (Delta) _o, higher crossover temperature T_max (> T*) and the corresponding large energy scale pseudogap (LPG) (Delta) _PG^L; (Delta) _PG^L approximately 3k_BT_max approximately (alpha) (Delta) _o ((alpha) equals 3 to 4 for Bi2212 and (alpha) equals 6 - 8 for La214). Furthermore, we report that T_c almost scales with p(Delta) _o over a wide p range, except for high doping levels (p/p_{o approximately}> 1.3), where T_c is very close to the BCS expectation (T_c equals 2(Delta) _o/4.3k_B). We discuss some scenarios for the superconducting transition, where the energy scale in determining T_c is expected to be of order p(Delta) _o.

Citation Download Citation

Migaku Oda, Naoki Momono, and Masayuki Ido "Energy scale in determining T_c of cuprate superconductors", Proc. SPIE 4058, Superconducting and Related Oxides: Physics and Nanoengineering IV, (6 September 2000); https://doi.org/10.1117/12.397853

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