Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: $Ab initio$ calculations

TL;DR

This paper proposes a spin-transfer mechanism for high-temperature ferromagnetism in polymerized fullerenes, supported by ab initio calculations showing strong exchange interactions that could explain room temperature ferromagnetism.

Contribution

It introduces a new mechanism involving spin and charge transfer from impurities to magnetically active fullerenes, supported by quantitative ab initio exchange interaction calculations.

Findings

Exchange interactions are in the range 0.1-0.3 eV.

Impurities induce magnetic activity in fullerenes.

High exchange interactions can explain room temperature ferromagnetism.

Abstract

A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C$_{60}$ molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH$_2$, or methyl group CH$_3$, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range $0.1\div 0.3 $ eV, that is, high enough to account for the room temperature ferromagnetism.