A systematic study of single molecule metallocenes with 4d and 3d transition metal atoms

TL;DR

This study systematically investigates the electronic and magnetic anisotropic properties of 4d and 3d transition metal metallocenes using first-principles calculations, revealing key factors influencing their magnetic anisotropy for spintronic applications.

Contribution

It provides new insights into how orbital ordering and charge states affect magnetic anisotropy in metallocenes, guiding future design of single molecule magnets.

Findings

Mo and Rh metallocenes exhibit anisotropy up to 20 Kelvin.

Anisotropy depends on orbital ordering, not just number of d electrons.

Cationic Mo-metallocene shows increased anisotropy up to 60 Kelvin.

Abstract

The realization of spin based devices is one of the most aspiring goals of spintronics research. Single molecule magnets are an important class of nanoscale magnetic systems with potential to realize different spintronic devices where each molecule can be used as a fundamental building block for devices. In this work, we have systematically investigated metallocenes, a class of single molecule magnets, with 4d and 3d transition metal elements for their electronic and magnetic anisotropic properties, using first-principles density functional theory. Among the seven 4d elements studied in this work, the largest anisotropy of about 20 Kelvin is obtained for Mo and Rh with uniaxial anisotropy. We found that the anisotropy does not increase with an increasing number of $d$ electrons; rather, it depends strongly on the orbital ordering of the $d$ states of the transition metal. Our calculations also show that the anisotropy of Mo-metallocene increases for cationic charge states to 60 Kelvin but with an easy-plane anisotropy. For 3d elements, the anisotropy of the molecules is calculated to be less than 10 Kelvin. We also have studied the role of ligands on the structural stability of these molecules and have provided a clear guideline to construct an appropriate model of molecules for theoretical studies.