Persistent Fermi Pockets and Robust Electron Pairing in Lightly Doped CuO${}_2$ Planes of Cuprate Superconductors

Abstract

High temperature superconductivity in cuprate superconductors is generally considered to be generated from doping the Mott insulators. The fundamental nature of the doped parent compounds as well as the microscopic origin of electron pairing remain critical issues in understanding the emergence of superconductivity. Here, using high-resolution spatially-resolved laser angle-resolved photoemission spectroscopy, we investigate the intrinsic electronic structures of the CuO${}_2$ planes in multilayer cuprates Bi${}_2$Sr${}_2$Ca${}_{n-1}$Cu${}_n$O${}_{2n+4+\delta }$ (n=5$\sim$8). The inner CuO${}_2$ planes are well shielded from the disorders and provide a rare and ideal platform to probe the intrinsic electronic phase diagram. We observe well-defined Fermi pockets with hole doping levels as low as 0.007, demonstrating an abrupt transition from the parent Mott insulator to a metallic state upon the introduction of an infinitesimal amount of doping. The innermost CuO${}_2$ planes (IP${}_0$) display gapless Fermi pockets, while the second innermost planes (IP${}_1$) exhibit anisotropic superconducting gaps up to $\sim$33meV, indicative of robust electron pairing coexisting with strong antiferromagnetic order. Our findings provide a revised framework for understanding the doping-driven transitions and pairing mechanisms in cuprate superconductors.

23 pages, 4 figures

References in corpus (27)

• Angle-resolved photoemission spectroscopy of the cuprate superconductors
• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Electronic Phase Diagram of High-T_c Cuprate Superconductors from a Mapping of the In-Plane Resistivity Curvature
• Missing Quasiparticles and the Chemical Potential Puzzle in the Doping Evolution of the Cuprate Superconductors
• Mobility of the Doped Holes and the Antiferromagnetic Correlations in Underdoped High-T_c Cuprates
• Phase competition in trisected superconducting dome
• Strength of the Spin-Fluctuation-Mediated Pairing Interaction in a High-Temperature Superconductor
• Doping Evolution of the Underlying Fermi Surface in La2-xSrxCuO4
• Development of a Vacuum Ultra-Violet Laser-Based Angle-Resolved Photoemission System with a Super-High Energy Resolution Better Than 1 meV
• High-Tc Superconductivity and Antiferromagnetism in Multilayered Copper Oxides - A New Paradigm of Superconducting Mechanism -
• New Developments in Laser-Based Photoemission Spectroscopy and its Scientific Applications: a Key Issues Review
• Electronic structure of the trilayer cuprate superconductor Bi${}_2$Sr${}_2$Ca${}_2$Cu${}_3$O${}_{10+\delta }$
• Evolution of the resistivity anisotropy in Bi_{2}Sr_{2-x}La_{x}CuO_{6+δ} single crystals for a wide range of hole doping
• Evolution of a Metal to Insulator Transition in Ca${}_{2-x}$Na${}_x$CuO${}_2$Cl${}_2$, as seen by ARPES
• Enhanced superconducting gaps in the tri-layer high-$T_c$ cuprate Bi${}_2$Sr${}_2$Ca${}_2$Cu${}_3$O${}_{10+\delta }$
• Doping evolution of the electronic structure in the single-layer cuprates Bi${}_2$Sr${}_{2-x}$La${}_x$CuO${}_{6+\delta }$: Comparison with other single-layer cuprates
• Visualizing the atomic scale electronic structure of the Ca2CuO2Cl2 Mott insulator
• Disappearance of Nodal Gap across the Insulator-Superconductor Transition in a Copper-Oxide Superconductor
• Gap anisotropy and universal pairing scale in a spin fluctuation model for cuprates
• Observation of small Fermi pockets protected by clean CuO2 sheets of a high-Tc superconductor
• Electronic Origin of High-Tc Maximization and Persistence in Trilayer Cuprate Superconductors
• Fully Gapped Single-Particle Excitations in the Lightly Doped Cuprates
• Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor
• Unveiling phase diagram of the lightly doped high-Tc cuprate superconductors with disorder removed
• Electronic Evolution from the Parent Mott Insulator to a Superconductor in Lightly Hole-Doped Bi2Sr2CaCu2O8+delta
• Evolution of the electronic structure from the insulator to the superconductor in Bi2Sr2-xLax(Ca,Y)Cu2O8+d
• Visualizing the Zhang-Rice singlet, molecular orbitals and pair formation in cuprate