Li states on a C-H vacancy in graphane: a first-principles study

• Published in: RSC advances Vol. 7; no. 63; pp. 39748 - 39757
• Main Authors: Mapasha, R. E, Molepo, M. P, Chetty, N
• Format: Journal Article
• Language: English
• Published: 01-01-2017
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c7ra06431d

Using a hybrid density functional theory approach, we have studied the effect of the interaction of a Li atom with a C-H pair vacancy defect (V
CH
) in a
graphane
monolayer on the thermodynamic stability, structural, magnetic and electronic properties, taking into account the effect of charge doping. We found that a Li atom and charge doping enhanced the thermodynamic stability of a V
CH
defective
graphane
monolayer. The Li-V
CH
system may likely act as a single deep donor, and can readily compensate the acceptor. The effects of Li introduce more occupied states in the band gap, and there exists strong hybridization between the C 2p states and Li 2s states at the vicinity of the Fermi level (
E
F
) responsible for the large magnetic moment noted. The −1 charge doping (Li
1−
-V
CH
) further populates the occupied states in the band gap, shifting the
E
F
towards the conduction band minimum. Consequently, the Li
1−
-V
CH
system possesses spintronic effects such as half-metallic ferromagnetic character and pronounced magnetism. The +1 charge doping (Li
1+
-V
CH
) removes some of the Li induced occupied states, slightly shifting the
E
F
towards the valence band maximum leading to a reduction in the magnetic moment. Our findings give an explanation of the origin of magnetism in a V
CH
defective
graphane
system and suggest a possible practical way of controlling it.
The Li ion enhances the V
CH
induced magnetism. The −1 charge doping shifts the Fermi level to the CBM further increasing magnetism. The +1 charge doping shifts the Fermi level to the VBM reducing magnetism.