Flat Chern Band in a Two-Dimensional Organometallic Framework

TL;DR

This paper proposes a first-principles design of a 2D organometallic framework that realizes a nearly flat Chern band, potentially enabling high-temperature fractional quantum Hall states in real materials.

Contribution

It introduces a novel 2D Indium-Phenylene Organometallic Framework design that achieves a nearly flat Chern band near the Fermi level, combining theoretical modeling with practical synthesis strategies.

Findings

Realizes a nearly flat Chern band in a 2D material

Constructs an effective four-band model matching first-principles results

Provides a synthesis strategy for topologically nontrivial organic materials

Abstract

By combining exotic band dispersion with nontrivial band topology, an interesting type of band structure, namely the flat chern band (FCB), has recently been proposed to spawn high-temperature fractional quantum hall states. Despite the proposal of several theoretical lattice models, however, it remains a doubt whether such a "romance of flatland" could exist in a real material. Here, we present a first-principles design of a two-dimensional (2D) Indium-Phenylene Organometallic Framework (IPOF) that realizes a nearly FCB right around the Fermi level by combining lattice geometry, spin-orbit coupling and ferromagnetism. An effective four-band model is constructed to reproduce the first-principles results. Our design in addition provides a general strategy to synthesize topologically nontrivial materials in virtue of organic chemistry and nanotechnology.