Magnetic properties in CdS monolayer doped with first-row elements: A density functional theory investigation

Using first-principles calculations, we have studied the structural, electronic, and magnetic properties in CdS monolayer doped with nonmagnetic (NM) atoms X (X = B, C, N, and O). The total magnetic moments are about 1.0, 2.0, 1.0, and 0.0 mu(B) per supercell for the B-, C-, N-, and O-doped systems, respectively. As the electronegativity of X element increases, the local magnetic moment tends to localize and the impurity states gradually approach the valence band maximum of the host CdS. We find that the CdS monolayer with one S atom per supercell substituted by a B or C atom is half-metallic (HM), while that with an N atom per supercell is a ferromagnetic (FM) semiconductor. As for the one-oxygen doped case, the system still remains a semiconductor. Upon two S atoms per supercell substituted by X (= B, C, and N) atom, the X-doped CdS systems exhibit various magnetic ground states. As a consequence of the competition between double-exchange and super-exchange, the two-B-doped CdS system displays NM and anti-magnetic (AFM) behaviors, while the two-C-doped CdS system shows HM ferromagnetism with a Curie temperature of 280 K. However, the two-N-doped CdS system is a semiconductor with weakly AFM ground state. Our study demonstrates that the NM elements doping is an efficient route to tune the magnetic and electronic properties in CdS monolayers. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim