https://doi.org/10.1140/epjb/s10051-022-00322-z
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
Received:
21
January
2022
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
