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arXiv · 1903.07466

Magnetization, d-wave superconductivity and non-Fermi liquid behavior in a crossover from dispersive to flat bands

Pramod Kumar·Tuomas I. Vanhala·Päivi Törmä
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Abstract

We explore the effect of inhomogeneity on electronic properties of the two-dimensional Hubbard model on a square lattice using dynamical mean-field theory (DMFT). The inhomogeneity is introduced via modulated lattice hopping such that in the extreme inhomogeneous limit the resulting geometry is a Lieb lattice, which exhibits a flat-band dispersion. The crossover can be observed in the uniform sublattice magnetization which is zero in the homogeneous case and increases with the inhomogeneity. Studying the spatially resolved frequency-dependent local self-energy, we find a crossover from Fermi-liquid to non-Fermi-liquid behavior happening at a moderate value of the inhomogeneity. This emergence of a non-Fermi liquid is concomitant of a quasi-flat band. For finite doping the system with small inhomogeneity displays $d$-wave superconductivity coexisting with incommensurate spin-density order, inferred from the presence of oscillatory DMFT solutions. The $d$-wave superconductivity gets suppressed for moderate to large inhomogeneity for any finite doping while the incommensurate spin-density order still exists.

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Pramod Kumar, Tuomas I. Vanhala, Päivi Törmä. 2019-03-18. Magnetization, d-wave superconductivity and non-Fermi liquid behavior in a crossover from dispersive to flat bands. https://doi.org/10.1103/physrevb.100.125141

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