# Superconductivity in repulsively interacting fermions on a diamond chain: Flat-band-induced pairing

@article{Kobayashi2016SuperconductivityIR, title={Superconductivity in repulsively interacting fermions on a diamond chain: Flat-band-induced pairing}, author={Keita Kobayashi and Masahiko Okumura and Susumu Yamada and Masahiko Machida and Hideo Aoki}, journal={Physical Review B}, year={2016}, volume={94}, pages={214501} }

To explore whether a flat-band system can accommodate superconductivity, we consider repulsively interacting fermions on the diamond chain, a simplest quasi-one-dimensional system that contains a flat band. Exact diagonalization and the density-matrix renormalization group (DMRG) are used to show that we have a significant binding energy of a Cooper pair with a long-tailed pair-pair correlation in real space when the total band filling is slightly below $1/3$, where the dispersive band…

## 37 Citations

Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics

- Physics
- 2020

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…

Wide applicability of high-T c pairing originating from coexisting wide and incipient narrow bands in quasi-one-dimensional systems

- Physics
- 2018

We study superconductivity in the Hubbard model on various quasi-one-dimensional lattices with coexisting wide and narrow bands originating from multiple sites within a unit cell, where each site…

Preformed pairs in flat Bloch bands

- PhysicsPhysical Review B
- 2018

In a flat Bloch band the kinetic energy is quenched and single particles cannot propagate since they are localized due to destructive interference. Whether this remains true in the presence of…

Optical spectral weight, phase stiffness, and Tc bounds for trivial and topological flat band superconductors

- Medicine, PhysicsProceedings of the National Academy of Sciences
- 2021

Borders are obtained for the optical spectral weight for flat-band superconductors that lead to upper bounds for the superfluid stiffness and the two-dimensional (2D) Tc.

Computational Design of Flat-Band Material

- Materials Science, MedicineNanoscale Research Letters
- 2018

This work has found that some pyrochlore oxides have quasi-flat band just below the Fermi level by first principles calculation and performed a spin-polarized band calculation for the hole-doped system and found that the ground state is ferromagnetic for some doping region.

Rhombi-chain Bose-Hubbard model: Geometric frustration and interactions

- PhysicsPhysical Review B
- 2018

We explore the effects of geometric frustration within a one-dimensional Bose-Hubbard model using a chain of rhombi subject to a magnetic flux. The competition of tunnelling, self-interaction and…

Designer flat bands in one-dimensional artificial systems

- Physics
- 2020

Certain lattices with specific geometries have one or more spectral bands that are strictly flat, i.e. the electron energy is independent of the momentum. This can occur robustly irrespective of the…

Flat-band engineering in tight-binding models: Beyond the nearest-neighbor hopping

- PhysicsPhysical Review B
- 2019

In typical flat-band models, defined as nearest-neighbor tight-binding models, flat bands are usually pinned to the special energies, such as top or bottom of dispersive bands, or band-crossing…

New class of flat-band models on tetragonal and hexagonal lattices: Gapped versus crossing flat bands

- Physics
- 2017

We propose a new class of tight-binding models where a flat band is either gapped from or crossing right through a dispersive band on two-band (i.e., two sites/unit cell) tetragonal and honeycomb…

FLEX $$+$$ + DMFT Analysis for Superconductivity in Systems with Coexisting Wide and Narrow Bands

- PhysicsSpringer Theses
- 2019

In this chapter, we study superconductivity and electron correlation effects in the bilayer Hubbard model with coexisting wide and incipient narrow bands originating from multiple sites within the…

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