Enormous enhancement of p-orbital magnetism and band gap in the lightly doped carbyne

Abstract

This paper presents a path to tailor adapted magnetic and electronic properties in carbyne. Although p-orbital magnetism is generally much weaker than d-orbital magnetism, we demonstrate that the charge fluctuation of the free radical electrons triggered by a time-varying electric dipole moment leads to enormous p-orbital magnetism. By introducing 25% arsenic and 12.5% fluorine into the monoatomic carbon chain, the magnetic moment of the arsenic atom reaches 2.9 μ_B, which is ∼1.3 times stronger than magnetic moment of bulk Fe. This magnetically optimized carbyne composite carries an exchange–correlation energy of 22 meV (∼270 K). On the other hand, we convert the carbyne (in beta-form) from metallic to a semiconducting state by using anionic dopants. After doping 12.5% nitrogen and 12.5% oxygen into the beta-carbyne, the semiconducting gap of this composite is optimized at 1.6 eV, which is 1.4 times larger than the band gap of bulk silicon.