Regular Article - Solid State and Materials
Theory for cuprate high-temperature superconductors in the underdoped regime: the singlet-bond superconductivity
Department of Physics, Niigata University, 950-2181, Niigata, Japan
Accepted: 17 March 2022
Published online: 25 April 2022
In the large U Hubbard model, the singlet-bond state (the two-electron bound state) different from the resonating valence bond (RVB) state is found to exist. Upon doping holes into the half-filled Hubbard model, the singlet-bond state changes from the immobile state to the translationally mobile state and the coherent singlet-bond superconducting state develops below the disordered immobile singlet-bond insulating phase. The superconducting phase has the doubled-size sublattice symmetry similar to the antiferromagnetic phase. The sublattice quasiparticle energy dispersions of the singlet-bond superconducting state can explain the experimentally observed unusual small hole-like Fermi pockets around and are consistent with the ARPES spectra observed in the zone-face and the zone-diagonal directions. The superconducting transition temperature is determined as , where is doping, , and varies monotonically from 3.77 for to 2.42 for .
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2022