Quantum anomalous Hall effect in metal-bis(dithiolene), magnetic properties, doping and interfacing graphene

TL;DR

This study demonstrates the realization of the quantum anomalous Hall effect in 2D metal-organic frameworks, showing how magnetic properties and doping can induce topologically protected edge states, with potential for tunable electronic applications.

Contribution

It introduces the first theoretical prediction of QAHE in specific MOFs and explores how doping and interfacing with graphene can control topological properties.

Findings

QAHE occurs in Mn, Fe, and Ru MOFs due to structural symmetry.

Electron doping shifts the Fermi level into the topological gap.

Fermi level tuning via electric fields enables switchable edge currents.

Abstract

The realization of the Quantum anomalous Hall effect (QAHE) in two dimensional (2D) metal organic frameworks (MOFs), (MC$_4$S$_4$)$_3$ with M = Mn, Fe, Co, Ru and Rh, has been investigated based on a combination of first-principles calculations and tight binding models. Our results for the magnetic anisotropy energy (MAE) reveal that the out-of-plane (in-plane) magnetization is favored for M = Mn, Fe, and Ru (Co, and Rh). Given the structural symmetry of (MC$_4$S$_4$)$_3$, the QAHE takes place only for M = Mn, Fe and Ru. Such a quantum anomalous Hall phase has been confirmed through the calculation of the Chern number, and examining the formation of topologically protected (metallic) edge states. Further electron ($n$-type) doping of the MOFs has been done in order to place the Fermi level within the non-trivial energy gap; where we find that in (RuC$_4$S$_4$)$_3$, in addition to the up-shift of the Fermi level, the MAE energy increases by 40\%. Finally, we show that in MOF/graphene (vdW) interfaces, the Fermi level tunning can be done with an external electric field, which controls the charge transfer at the MOF/graphene interface, giving rise to switchable topologically protected edge currents in MOFs.