Photoemission study of the superconducting-gap symmetry in electron-doped high-Tc superconductors

To study the superconducting-gap symmetry in electron-doped HTSC, we performed a high-resolution ARPES on Pr0.89LaCe0.11CuO4 (optimally-doped, T-c = 26 K). Obtained momentum dependence of the superconducting gap is basically consistent with the d(x2-y2)-wave symmetry, but obviously deviates from the monotonic form of the d(x2-y2) gap function. The maximum superconducting gap is not located at the zone boundary as expected from a simple d(x2-y2)-wave, but observed at the so-called hot spot where the antiferromagnetic spin fluctuation strongly couples to the electrons on the Fermi surface. This ARPES result suggests that the spin-correlation plays an essential role in the pairing mechanism of electron-doped HTSC. (c) 2007 Elsevier B.V. All rights reserved.