Superconductivity from Flat Dispersion Designed in Doped Mott Insulators

TL;DR

This paper proposes a geometric design strategy to enhance superconductivity in doped Mott insulators by creating flat band dispersions near the Fermi level, supported by numerical studies and multi-band system proposals.

Contribution

It introduces a novel lattice design principle to control superconducting instability through flat band engineering near the Fermi level.

Findings

Numerical results show large enhancement of spin-gap and pairing regions.

Design of multi-band systems where intersite Coulomb repulsion drives pairing.

Guidelines for lattice geometry to optimize superconducting properties.

Abstract

Routes to enhance superconducting instability are explored for doped Mott insulators. With the help of insights for criticalities of metal-insulator transitions, geometrical design of lattice structure is proposed to control the instability. A guideline is to explicitly make flat band dispersions near the Fermi level without suppressing two-particle channels. In a one-dimensional model, numerical studies show that our prescription with finite-ranged hoppings realizes large enhancement of spin-gap and pairing dominant regions. We also propose several multi-band systems, where the pairing is driven by intersite Coulomb repulsion.