Pseudogap, Superconducting Gap, and Fermi Arc in High-T_{\text{c}} Cuprates Revealed by Angle-Resolved Photoemission Spectroscopy

概要

論文の詳細を見る
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 T_{\text{c}} 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 \Delta_{0}) and in the anti-nodal region (characterized by \Delta^{*}). Dichotomy between them has been demonstrated from the material, doping, and temperature dependence of the energy gap. While \Delta^{*} at the same doping level is approximately material independent, \Delta_{0} shows a strong material dependence tracking the magnitude of T_{\text{c,max}}. The anti-nodal gap does not close at T_{\text{c}} in contrast to the gap near the node which follows something closer to a BCS-like temperature dependence. An effective superconducting gap \Delta_{\text{sc}} defined at the end point of the Fermi arc is found to be proportional to T_{\text{c}}'s in various materials.
2012-01-15