Ferromagnetism and optical properties of SnS2 doped with two impurities: first-principles calculations

Abstract

Based on the first principles of the GGA method, the magnetic and optical properties of intrinsic SnS₂; Fe, Cr mono-doped SnS₂; and (Fe, Cr) co-doped SnS₂ are studied. The results show that the ground states of Fe, Cr mono-doped SnS₂ are spin polarized, and the magnetic moments caused are 1.99 μ_B and 3.00 μ_B, respectively. The magnetic moment of Fe mono-doped SnS₂ is mainly produced by Fe:3d orbitals, and the magnetic moment of Cr mono-doped SnS₂ is mainly produced by Cr:3d and Sn:4d orbitals. We calculate that in the (Fe, Cr) co-doped SnS₂ system, Fe, Cr and the adjacent S atoms form a strong hybrid, that is, the closest S atom between Fe and Cr atoms mediates the spin polarization and ferromagnetic (FM) coupling. This promotes the formation of a Fe:3d–S:3p–Cr:3d coupling chain, so that (Fe, Cr) co-doped SnS₂ obtains FM stability. In addition, with the introduction of Fe and Cr atoms, the absorption coefficient is the largest in the long-wavelength infrared region of 0.23–1.63 eV. This shows that Fe and Cr doping can make up for the lack of absorption of intrinsic materials in the infrared region. In summary, Fe, Cr doped SnS₂ dilute magnetic semiconductors may be a good candidate in the field of spintronic devices.