Role of charge transfer in hybridization-induced spin transition in metal-organic molecules

TL;DR

This paper investigates how charge transfer influences spin-state switching in metal-organic molecules, combining theoretical modeling and DFT calculations to understand and propose mechanisms for spin-crossover relevant to molecular spintronics.

Contribution

It introduces a minimal many-body model for spin-crossover and demonstrates the critical role of charge transfer in Ni-porphyrin, proposing a strain-based switching mechanism.

Findings

Charge transfer is crucial for spin-state determination in Ni-TPP.

A minimal model captures the physics of spin-crossover.

Mechanical strain can induce spin transition without structural isomerization.

Abstract

The spin-crossover in organometallic molecules constitutes one of the most promising routes towards the realization of molecular spintronic devices. In this article, we explore the hybridization-induced spin-crossover in metal-organic complexes. We propose a minimal many-body model that captures the essence of the spin-state switching in a generic parameter space, thus providing insight into the underlying physics. Combining the model with density functional theory (DFT), we then study the spin-crossover in isomeric structures of Ni-porphyrin (Ni-TPP). We show that metal-ligand charge transfer plays a crucial role in the determination of the spin-state in Ni-TPP. Finally, we propose a spin-crossover mechanism based on mechanical strain, which does not require a switch between isomeric structures.