Pairing and non-Fermi liquid behavior in partially flat-band systems
Abstract
While multiband systems are usually considered for flat-band physics, here we study one-band models that have flat portions in the dispersion to explore correlation effects in the 2D repulsive Hubbard model in an intermediate coupling regime. The FLEX+DMFT~(the dynamical mean-field theory combined with the fluctuation exchange approximation) is used to show that we have a crossover from ferromagnetic to antiferromagnetic spin fluctuations as the band filling is varied, which triggers a crossover from triplet to singlet pairings with a peculiar filling dependence that is dominated by the size of the flat region in the dispersion. A curious manifestation of the flat part appears as larger numbers of nodal lines associated with pairs extended in real space. We further detect non-Fermi liquid behavior in the momentum distribution function, frequency dependence of the self-energy and spectral function. These indicate correlation physics peculiar to flat-band systems.
Cite
@article{arxiv.1903.09888,
title = {Pairing and non-Fermi liquid behavior in partially flat-band systems},
author = {Sharareh Sayyad and Edwin W. Huang and Motoharu Kitatani and Mohammad-Sadegh Vaezi and Zohar Nussinov and Abolhassan Vaezi and Hideo Aoki},
journal= {arXiv preprint arXiv:1903.09888},
year = {2020}
}
Comments
7+2 pages