Computational Analysis of Interface-Driven Spin-Orbit Coupling in Molecular Adsorbates on Transition Metal Dichalcogenides

TL;DR

This study uses computational methods to show how molecular and substrate interactions can significantly enhance spin-orbit coupling in surface-adsorbed molecules, advancing molecular spintronics without complex synthesis.

Contribution

It demonstrates that interfacial hybridization between molecules and TMD substrates can induce substantial SOC splitting, a novel approach for designing spintronic materials.

Findings

Zn-phthalocyanine on MoS2 achieves ~8 meV SOC splitting

Self-assembled ZnPC chains increase SOC splitting to ~20 meV

Interfacial hybridization is key to SOC enhancement in molecular adsorbates

Abstract

Spin-orbit coupling (SOC) lifts molecular orbital degeneracy, enabling bi-level electronic platforms suitable for next-generation digital devices. However, common light-atom molecular feedstocks exhibit weak SOC due to the absence of heavy elements. To enhance SOC without synthesizing new materials, we leverage interfacial interactions between molecules and transition-element-based solid-state materials. This computational study investigates SOC splitting in metal-phthalocyanine adsorbed on transition metal dichalcogenides (TMDs) using density functional theory (DFT). The enhanced SOC splitting is attributed to strong orbital hybridization at the molecule-substrate interface. Specifically, Zn-phthalocyanine (ZnPC) on monolayer MoS2 achieves a notable SOC splitting of ~8 meV. Furthermore, when ZnPC forms self-assembled chains on MoS2, the splitting increases to ~20 meV, driven by the formation of hybrid bands modulated by molecular periodicity. These findings highlight the role of interfacial and intermolecular interactions in inducing and enhancing SOC in surface-adsorbed molecules, providing a new strategy for molecular spintronic materials without complex synthetic efforts.