Bond excitations in the pseudogap phase of the Hubbard model
Abstract
Using the dynamical cluster approximation, we calculate the correlation functions associated with the nearest-neighbor bond operator which measure the z component of the spin exchange in the two-dimensional Hubbard model with U equal to the bandwidth. We find that in the pseudogap region, the local bond susceptibility diverges at T=0 . This shows the existence of degenerate bond spin excitation and implies quantum criticality and bond order formation when long-range correlations are considered. The strong correlation between excitations on parallel neighboring bonds suggests bond singlet dimerization. The suppression of divergence for n<≈0.78 implies that for these model parameters, this is a quantum critical point which separates the unconventional pseudogap region characterized by bond order from a conventional Fermi liquid.
- Publication:
-
Physical Review B
- Pub Date:
- December 2008
- DOI:
- 10.1103/PhysRevB.78.241101
- arXiv:
- arXiv:0806.0815
- Bibcode:
- 2008PhRvB..78x1101M
- Keywords:
-
- 71.10.Fd;
- 75.40.Mg;
- 74.72.-h;
- 74.25.Jb;
- Lattice fermion models;
- Numerical simulation studies;
- Cuprate superconductors;
- Electronic structure;
- Condensed Matter - Strongly Correlated Electrons;
- Condensed Matter - Superconductivity
- E-Print:
- 5 pages, 5 figures