Observation of small Fermi pockets protected by clean CuO2 sheets of a high-Tc superconductor

Abstract

The superconductivity of high transition temperature (Tc) occurs in copper oxides with carrier-doping to an antiferromagnetic (AF) Mott insulator. This discovery more than thirty years ago immediately led to a prediction about the formation of a small Fermi pocket. This structure, however, has not yet been detected, while it could be a key element in relating high-Tc superconductivity to Mott physics. To address this long-standing issue, we investigate the electronic structure of a five-layered Ba2Ca4Cu5O10(F,O)2 with inner CuO2 planes demonstrated to be cleanest ever in cuprates. Most surprisingly, we find small Fermi surface (FS) pockets closed around (pi/2,pi/2) consistently by angle-resolved photoemission spectroscopy (ARPES) and quantum oscillation measurements. The d-wave superconducting gap opens along the pocket, revealing the coexistence between the superconductivity and AF order in the same CuO2 sheet. Our data further indicate that the superconductivity can occur without contribution from the states near the antinodal region, which are shared by other competing excitations such as the charge density wave (CDW) and pseudogap states. This will have significant implications for understanding the superconductivity and puzzling Fermi arc phenomena in cuprates.

References in corpus (14)

• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor
• Electron pockets in the Fermi surface of hole-doped high-Tc superconductors
• Direct evidence for a competition between the pseudogap and high temperature superconductivity in the cuprates
• Quantum Oscillations in the Underdoped Cuprate YBa2Cu4O8
• Anomalous high energy dispersion in photoemission spectra from insulating cuprates
• Competition between d-wave superconductivity and antiferromagnetism in the 2D Hubbard model
• Asymmetry of the electronic states in hole- and electron-doped cuprates: Exact diagonalization study of the t-t'-t''-J model
• Point nodes persisting far beyond Tc in Bi2212
• Imaging nanoscale Fermi surface variations in an inhomogeneous superconductor
• High-field Hall resistivity and magnetoresistance in electron-doped Pr_2-xCe_xCuO_{4-δ}
• Nodeless superconductivity arising from strong (pi,pi) antiferromagnetism in the infinite-layer electron-doped cuprate Sr1-xLaxCuO2
• Structural origin of apparent Fermi surface pockets in angle-resolved photoemission of Bi${}_2$Sr${}_{2-x}$La${}_x$CuO${}_{6+\delta }$
• Band Structure of Overdoped Cuprate Superconductors: Density Functional Theory Matching Experiments