A Bespoke Single-Band Hubbard Model Material

TL;DR

This paper proposes designing a real material that embodies the single-band Hubbard model using ab initio methods, enabling experimental study of its complex quantum phenomena like d-wave superconductivity.

Contribution

It introduces a novel approach of using electronic structure calculations to create a material that directly realizes the Hubbard model, facilitating experimental exploration.

Findings

Identification of candidate materials with the desired electronic properties

Prediction of a regime exhibiting d-wave superconductivity

Proposal of specific materials for synthesis and experimental validation

Abstract

The Hubbard model, which augments independent-electron band theory with a single parameter to describe electron-electron correlations, is widely regarded to be the `standard model' of condensed matter physics. The model has been remarkably successful at addressing a range of correlation effects in solids, but beyond one dimension its solution is intractable. Much current research aims, therefore, at finding appropriate approximations to the Hubbard model phase diagram. Here we take the new approach of using ab initio electronic structure methods to design a material whose Hamiltonian is that of the single-band Hubbard model. Solution of the Hubbard model will then be available through measurement of the material's properties. After identifying an appropriate crystal class and several appropriate chemistries, we use density functional theory and dynamical mean-field theory to screen for the desired electronic band structure and metal-insulator transition. We then explore the most promising candidates for structural stability and suitability for doping and propose specific materials for subsequent synthesis. Finally, we identify a regime -- that should manifest in our bespoke material -- in which the single-band Hubbard model on a triangular lattice exhibits exotic d-wave superconductivity.