Dessau, Shen, and Marshall reply

Abstract

Dessau, Shen, and Marshall Reply: In our Letter, we reported on high energy-resolution angle-resolved photoemission (ARPES) data taken from three Bi2212 samples [1]. All of these samples showed a gap anisotropy in the a-b plane which is very much larger than in conventional superconductors. This was the main point of our paper, and precluded the possibility of the isotropic ^wave gap A^ =A^o. We further compared our data to the k-space dependences that one would expect from other more complicated forms of the order parameter, including a simple form for the extended ^--wave gap A^ex -[QOs{kxa)-^cos{kya)] and the d^i^yi wave gap A^ --[cos(kxa) -cos(kya)], as well as other suggestions in the literature such as the mixed symmetry order parameter s + id. The direction of the gap anisotropy Uiat our measurement displayed-maximum near the M point (/r,0) and minimum near the V-XiV) zone diagonal -was consistent with the d^i-yi and s+id gaps, but was inconsistent with the simplest extended ^--wave gap (e.g.

Hole pockets in thet-Jmodel

“…Then, it seems that in a recent photoemission study by Aebi et al [22], structures which are very consistent with such a shadow band scenario have indeed been observed. Moreover, another key feature of the dispersion relation for a single hole, namely the extended flat region near (π, 0) [23,24] has also been found as an universal feature of high temperature superconductors [25,26] Adopting a rigid band/hole pocket scenario thus would explain many experiments in a very simple and natural way, which moreover is remarkably consistent with the existing numerical data as a whole.…”

Effects of transverse electron dispersion on photo-emission spectra of quasi-one-dimensional systems

“…Similar features are also observed in some quasi-two-dimensional high-T c superconductors whose ARPES spectra have the so-called peak-dip-hump structure where the hump spreads up to energies far from the Fermi surface [2]. As far as wide frequency scale is considered the measurements [1] are in qualitative agreement with our RPA result for strictly one-dimensional band dispersion [3].…”

“…The angle resolved photoemission (ARPES) experiments in some quasi-one-dimensional materials, particularly in Bechgaard salts like (TMTSF) 2 PF 6 , show a wide feature in the spectral density at frequency scale of the order of plasmon frequency, and do not show quasi-particle peaks, main ingredients in spectra of three-dimensional Fermi liquids [1]. Similar features are also observed in some quasi-two-dimensional high-T c superconductors whose ARPES spectra have the so-called peak-dip-hump structure where the hump spreads up to energies far from the Fermi surface [2].…”

Temperature dependence of the electron chemical potential in YBa2Cu3O6+δ

“…For the physical value of t ≈ 3 it means β 2 ≈ 0.3. Angle resolved photoemission experiments [20] indicate a smaller value of β 2 ≃ 0.1, which can be modelled by adding a small diagonal hopping term to the original t-J Hamiltonian. While being crucial in some experiments (such as the Hall effect), when pairing is considered, the exact value of β 2 is not very important as long as it is small.…”