The Mechanism of Spin-Phonon Relaxation in Endohedral Metallofullene Single Molecule Magnets

TL;DR

This paper investigates the spin-phonon coupling mechanisms in fullerene-based single-molecule magnets using ab initio calculations, revealing internal ionic motion as the main factor limiting their magnetic relaxation properties.

Contribution

It provides the first computational analysis of spin dynamics in EMF-based SMMs, highlighting the role of internal ionic motion in spin relaxation.

Findings

Internal ionic motion controls spin relaxation.

Fullerene cage stabilizes structure without affecting low-energy phonons.

DyScS@C82 exhibits one of the highest blocking temperatures.

Abstract

This study presents the first-ever investigation of spin-phonon coupling mechanisms in fullerene-based single-molecule magnets (SMMs) using ab initio CASSCF combined with DFT calculations. While lanthanide-based SMMs, particularly those with DyIII ions, are known for their impressive blocking temperatures and relaxation barriers, endohedral metallofullerene (EMFs) offer a unique platform for housing low-coordinated lanthanides within rigid carbon cages. We have explored the spin dynamics of in DyScS@C82 exhibiting among the highest blocking temperature (TB) reported. Through our computational analysis, we reveal that while the fullerene cage enhances crystal field splitting and provides structural stability without significantly contributing to spin-relaxation-driving low-energy phonons, the internal ionic motion emerges as the primary factor controlling spin relaxation and limiting blocking temperature. This computational investigation into the spin dynamics of EMF-based SMMs provides key insights into their magnetic behaviour for the first time an