Cofermion Theory for Pseudogap Phenomena and Superconducting Mechanism of Underdoped Cuprate Superconductors

Abstract

We study pseudogap phenomena and Fermi-arc formation experimentally observed in typical two dimensional doped Mott insulators, namely, underdoped cuprate superconductors. To develop a physically unequivocal theory, we start from the slave-boson mean-field theory for the Hubbard model on a square lattice. Our crucial step is to further take into account the charge dynamics and fluctuations. The extra charge fluctuations seriously modify low-energy single-particle spectra of doped Mott insulators near the Fermi level: An electron added around an empty site (or a hole added around a doubly occupied site) constitutes composite fermion (cofermion), called holo-electron (or doublo-hole) at low energy in distinction from the normal quasiparticles. These unexplored composite fermions substantiate the extra charge fluctuation. We show that the quasiparticles hybridize with the holo-electrons and doublo-holes. The resultant hybridization gap is identified as the pseudogap observed in the underdoped region of the high-T_c cuprates. Because the Fermi level crosses the top (bottom) of the low-energy band formed just below (above) the hybridization gap in the hole-doped (electron-doped) case, it causes a Fermi-surface reconstruction, namely, a topological change in the Fermi surface forced by the penetration of zeros of the quasiparticle Green function. This reconstruction signals the emergence of a non-Fermi-liquid phase. The pseudogap, and the resultant formation of pocket or arc of the Fermi surface reproduce the experimental results for the cuprate superconductors in the underdoped region. The pairing channel opens not only between two quasiparticles but also between a quasiparticle and a cofermion. This pairing solves the puzzle of the dichotomy between the d-wave superconductivity and the precursors of the the insulating gap in the antinodal region.

27 pages, 14 figures

References in corpus (18)

• A `checkerboard' electronic crystal state in lightly hole-doped Ca_{2-x}Na_{x}CuO_{2}Cl_{2}
• Magnetic order in the pseudogap phase of high-$T_C$ superconductors
• Polar Kerr Effect Measurements of YBa2Cu3O6+x: Evidence for Broken Symmetry Near the Pseudogap Temperature
• Distinct Fermi-Momentum Dependent Energy Gaps in Deeply Underdoped Bi2212
• Evolution of electronic structure of doped Mott insulators - reconstruction of poles and zeros of Green's function
• Variational Monte Carlo Method Combined with Quantum-Number Projection and Multi-Variable Optimization
• Asymmetry of the electronic states in hole- and electron-doped cuprates: Exact diagonalization study of the t-t'-t''-J model
• Doped high-Tc cuprate superconductors elucidated in the light of zeros and poles of electronic Green's function
• Gapless quantum spin liquid, stripe and antiferromagnetic phases in frustrated Hubbard models in two dimensions
• Does Simple Two-Dimensional Hubbard Model Account for High-Tc Superconductivity in Copper Oxides?
• Pseudogap and Mott Transition Studied by Cellular Dynamical Mean Field Theory
• Universality Classes of Metal-Insulator Transitions in Strongly Correlated Electron Systems and Mechanism of High-Temperature Superconductivity
• Quantum and Topological Criticalities of Lifshitz Transition in Two-Dimensional Correlated Electron Systems
• Absence of time reversal symmetry breaking in La_{2-x}Sr_{x}CuO_{4}
• Composite-Fermion Theory for Pseudogap, Fermi Arc, Hole Pocket, and Non-Fermi-Liquid of Underdoped Cuprate Superconductors
• Gaussian-Basis Monte Carlo Method for Numerical Study on Ground States of Itinerant and Strongly Correlated Electron Systems
• Quantum critical "opalescence" around metal-insulator transitions
• Exact Integration of the High Energy Scale in Doped Mott Insulators

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• Emergence of electronic modes by doping Kondo insulators in the Kondo lattice and periodic Anderson models
• Signatures of the Fermi surface reconstruction of a doped Mott insulator in a slab geometry
• Pseudogap and strange metal states in the square-lattice Hubbard model: A comprehensive study
• Emergence and evolution of electronic modes with temperature in spin-gapped Mott and Kondo insulators
• Electronic modes induced by spin and charge perturbations in Mott and Kondo insulators