Origin of p-type half-metallic ferromagnetism in carbon-doped BeS: First-principles characterization

Ab-Initio calculations are used to investigate the electronic and magnetic properties of carbon-doped at Be (C@Be) and S (C@S) sites in BeS semiconductor. Structural stability of both (C@Be and C@S) doped systems is taken into account by calculating the formation energies. We found that C@Be doped system maintains its non-magnetic insulating behaviour with smaller band gap of 0.6 eV as compared to bulk. On the other hand, when C-doped at S-site (C@S), a half-metallic ferromagnetic state induced which can be explained on the basis of electronegativity difference between dopant atom and replaced cations. The C 2p orbitals are mainly responsible for the metallicity and magnetism with stable moment of 1.06 μB/C atom. Interestingly, the magnetic ground state i.e., ferromagnetic (FM) or anti-ferromagnetic (AFM) depends on the distance between C-atoms. A most stable-ferromagneting ordering is evident when the distance between two C atoms is very small ≈ 3.46 Å, due to strong C-C coupling with high magnetic transition temperature of Tc = 814 K. However, it is noticed that long range ferromagnetic clustering are not favourable. Our calculations demand experimental investigations of electronic and magnetic properties in C-doped BeS.