Theoretical Study of Magnetic Moments Induced by Defects at the SiC (110) Surface

TL;DR

This study uses first principles calculations to explore how various surface defects on SiC(110) influence local magnetic moments, revealing defect-specific magnetic behaviors mainly driven by carbon orbitals.

Contribution

It provides a detailed theoretical analysis of defect-induced magnetism on SiC(110), highlighting the role of different defects and their magnetic arrangements.

Findings

Si vacancies induce magnetic moments up to 0.7 μB on nearby carbon atoms.

Adsorption of H or F at Si sites also induces localized magnetic moments.

Magnetic ordering varies from ferromagnetic to antiferromagnetic depending on the defect.

Abstract

The effect of different surface defects on the atomic and electronic structures of cubic $\beta$-SiC(110) surface are studied by means of a first principles calculation based on Density Functional Theory using the SIESTA code. In the calculations, the possibility of different spin population at each atom is allowed. We find that while adsorption of oxygen or nitrogen and adsorption of hydrogen at the C surface carbon atoms do not induce magnetic moments on SiC(110); Si vacancies, substitutional C at the Si site and H or F adsorbed at the silicon surface sites induce localized magnetic moments as large as 0.7 $\mu_{B}$ at the carbon atoms close to the defect. The local magnetic moment arrange ment varies from ferromagnetic in the case of H adsorption to antiferromagnetic in the Si vacancy and substitutional C cases. The case of H adsorption at the Si surface atoms is discussed in detail. It is concluded that magnetism is mainly due to the local character of the C valence orbitals.