Ferromagnetism in Carbon doped Zinc Oxide Systems

TL;DR

This study uses density functional calculations to explore how carbon doping induces ferromagnetism in ZnO clusters and solids, revealing the role of dimensionality and bonding in magnetic interactions.

Contribution

It provides new insights into the magnetic properties of carbon-doped ZnO systems and highlights the influence of structure and bonding on ferromagnetism.

Findings

Doping induces approximately 2 μB magnetic moments in all systems.

Ferromagnetic interaction occurs in systems with two carbon impurities, except when sharing the same Zn atom.

Enhanced magnetic interaction in solids emphasizes the role of dimensionality.

Abstract

We report spin polarized density functional calculations of ferromagnetic properties of a series of ZnO clusters and solid containing one or two substitutional carbon impurities. We analyze the eigen value spectra, spin densities and molecular orbitals, and induced magnetic moments for ZnC, Zn$_{2}$C, Zn$_{2}$OC, carbon substituted clusters Zn$_{n}$O$_{n}$ (n=3--10, 12) and ZnO solid. The results show that the doping induces magnetic moment of the $\sim$2 $\mu_{B}$ in all the cases. All the systems with two carbon impurities show ferromagnetic interaction except when the carbon atoms share the same Zn atom as the nearest neighbor. This ferromagnetic interaction is predominantly mediated via $\pi$ bonds in ring structures and through $\pi$ and $\sigma$ bonds in three dimensional structure. The calculations also show that the interaction is significantly enhanced in solid, bringing out the role of dimensionality of Zn-O network connecting two carbon atoms.