"Pseudogap, Superconducting Gap, and Fermi Arc in High-Tc Cuprates Revealed by Angle-Resolved Photoemission Spectroscopy"

Teppei Yoshida: Makoto Hashimoto, Inna M. Vishik, Zhi-Xun Shen, and Atsushi Fujimori ; J. Phys. Soc. Jpn., 12/26/11.

Additional Authors: Makoto Hashimoto, Inna M. Vishik, Zhi-Xun Shen, and Atsushi Fujimori

Abstract:

We present an overview of angle-resolved photoemission spectroscopy (ARPES) studies of high-temperature cuprate superconductors aiming at elucidating the relationship between the superconductivity, the pseudogap, and the Fermi arc. ARPES studies of underdoped samples show a momentum dependence of the energy gap below Tc which deviates from a simple d-wave form, suggesting the coexistence of multiple energy scales in the superconducting state. Hence, two distinct energy scales have been introduced, namely, the gap near the node (characterized by Δ0) and in the anti-nodal region (characterized by Δ*). Dichotomy between them has been demonstrated from the material, doping, and temperature dependence of the energy gap. While Δ* at the same doping level is approximately material independent, Δ0 shows a strong material dependence tracking the magnitude of Tcmax. The anti-nodal gap does not close at Tc in contrast to the gap near the node which follows something closer to a BCS-like temperature dependence. An effective superconducting gap Δsc defined at the end point of the Fermi arc is found to be proportional to Tc‘s in various materials.