title: Point nodes persisting far beyond Tc in Bi2212.
abstract: In contrast to a complex feature of antinodal state, suffering from competing orders, the pairing gap of cuprates is obtained in the nodal region, which therefore holds the key to the superconducting mechanism. One of the biggest question is whether the point nodal state as a hallmark of d-wave pairing collapses at Tc like the BCS-type superconductors, or it instead survives above Tc turning into the preformed pair state. A difficulty in this issue comes from the small magnitude of the nodal gap, which has been preventing experimentalists from solving it. Here we use a laser ARPES capable of ultrahigh-energy resolution, and detect the point nodes surviving far beyond Tc in Bi2212. By tracking the temperature evolution of spectra, we reveal that the superconductivity occurs when the pair-breaking rate is suppressed smaller than the single-particle scattering rate on cooling, which governs the value of Tc in cuprates.
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Malaeb
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sasagawa
authors.affiliation: Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sakamoto
authors.affiliation: Energy Materials Laboratory, Toyota Technological Institute, Nagoya 468-8511, Japan.
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Takeuchi
authors.affiliation: Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tohyama
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shin