Chern insulators and high Curie temperature Dirac half-metal in two-dimensional metal-organic frameworks

TL;DR

This study uses density-functional theory to identify 2D metal-organic frameworks as Chern insulators with sizable gaps and high Curie temperature Dirac half-metals, promising for spintronics and topological quantum devices.

Contribution

It reveals that specific 2D MOFs are Chern insulators with sizable gaps and high Curie temperature Dirac half-metals, advancing topological materials and spintronics applications.

Findings

X(C21H15N3) (X=Ti, Zr, Ag, Au) are Chern insulators with ~7.1 meV gaps.

Mn(C21H15N3) is a Dirac half-metal with Curie temperature up to 156 K.

The Chern insulator phase results from band inversion and ferromagnetism.

Abstract

Two-dimensional (2D) magnetic materials with nontrivial topological states have drawn considerable attention recently. Among them, 2D metal-organic frameworks (MOFs) are standing out due to their advantages, such as the easy synthesis in practice and less sensitivity to oxidation that are distinctly different from inorganic materials. By means of density-functional theory calculations, we systematically investigate the electronic and topological properties of a class of 2D MOFs X(C21H15N3) (X = transition metal element from 3d to 5d). Excitingly, we find that X(C21H15N3) (X = Ti, Zr, Ag, Au) are Chern insulators with sizable band gaps (~7.1 meV). By studying a four-band effective model, it is revealed that the Chern insulator phase in X(C21H15N3) (X = Ti, Zr, Ag, Au) is caused cooperatively by the band inversion of the p orbitals of the C21H15N3 molecule and the intrinsic ferromagnetism of X(C21H15N3). Additionally, Mn(C21H15N3) is a Dirac half-metal ferromagnet with a high Curie temperature up to 156 K. Our work demonstrates that 2D MOFs X(C21H15N3) are good platforms for realizing Quantum anomalous Hall effect and designing novel spintronic devices based on half-metals with high-speed and long-distance spin transport.