Superconducting Gap in the Hubbard Model and the Two-Gap Energy Scales of High- Tc Cuprate Superconductors
Markus Aichhorn, Enrico Arrigoni, Zhongbing Huang +1 more
Recent experiments (angle-resolved photoemission spectroscopy and Raman) suggest the presence of two distinct energy gaps in high-temperature superconductors (HTSC), exhibiting different doping dependences. The results of a variational cluster approach to the superconducting state of the two-dimensional Hubbard model are presented which show that this model qualitatively describes this gap dichotomy. The antinodal gap increases with less doping, a behavior long considered as reflecting the general gap behavior of the HTSC. On the other hand, the near-nodal gap does even slightly decrease with underdoping. An explanation of this unexpected behavior is given which emphasizes the crucial role of spin fluctuations in the pairing mechanism.
arXiv:cond-mat/0702391•Physical Review Letters•Dec 17, 2007•35 citations