Superconductivity, Charge Density Wave, and Supersolidity in Flat Bands with a Tunable Quantum Metric

Johannes S. Hofmann, Erez Berg, Debanjan Chowdhury

Research output: Contribution to journalArticlepeer-review

Abstract

Predicting the fate of an interacting system in the limit where the electronic bandwidth is quenched is often highly nontrivial. The complex interplay between interactions and quantum fluctuations driven by the band geometry can drive competition between various ground states, such as charge density wave order and superconductivity. In this work, we study an electronic model of topologically trivial flat bands with a continuously tunable Fubini-Study metric in the presence of on-site attraction and nearest-neighbor repulsion, using numerically exact quantum Monte Carlo simulations. By varying the electron filling and the minimal spatial extent of the localized flat-band Wannier wave functions, we obtain a number of intertwined orders. These include a phase with coexisting charge density wave order and superconductivity, i.e., a supersolid. In spite of the nonperturbative nature of the problem, we identify an analytically tractable limit associated with a "small"spatial extent of the Wannier functions and derive a low-energy effective Hamiltonian that can well describe our numerical results. We also provide unambiguous evidence for the violation of any putative lower bound on the zero-temperature superfluid stiffness in geometrically nontrivial flat bands.

Original languageEnglish
Article number226001
JournalPhysical review letters
Volume130
Issue number22
DOIs
StatePublished - 2 Jun 2023

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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