Tunneling studies on the energy gap evolution of Bi2Sr2CaCu2O8+8

Migaku Oda; Naoki Momono; Masayuki Ido

doi:10.1117/12.452268

7 November 2002 Tunneling studies on the energy gap evolution of Bi₂Sr₂CaCu₂O_8+δ

Migaku Oda, Naoki Momono, Masayuki Ido

Proceedings Volume 4811, Superconducting and Related Oxides: Physics and Nanoengineering V; (2002) https://doi.org/10.1117/12.452268
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

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 ~T_max, 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 T_co for d-wave superconductors, and then evolves into the SC-gap below T_c,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 T_c nearly scales with the product of Δ₀ and p, k_BT_c~pΔ₀' the effective SC gap is ~pΔ₀ in high T_c cuprates, instead of Δ₀ in conventional BCS superconductors.

Citation Download Citation

Migaku Oda, Naoki Momono, and Masayuki Ido "Tunneling studies on the energy gap evolution of Bi₂Sr₂CaCu₂O_8+δ", Proc. SPIE 4811, Superconducting and Related Oxides: Physics and Nanoengineering V, (7 November 2002); https://doi.org/10.1117/12.452268

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