Structural, optical and magnetic properties of cobalt-doped CdS dilute magnetic semiconducting nanorods

Nanostructures of dilute magnetic semiconductors (DMS) in which a part of host material is replaced by a magnetic dopant are the promising candidates for spintronic devices. Pure and cobalt-doped DMS nanorods of CdS have been synthesized by solvothermal method. The effect of doping as well as the size of synthesized nanorods on structural, optical, and magnetic properties has been investigated. Transmission electron microscopy confirms the nanorodsʹ morphology with an average diameter between 7 and 11 nm. Structural study reveals the formation of single phase hexagonal wurtzite structure of CdS with P63mc space group. UV–visible absorption spectra confirms that the band gap of the synthesized nanorods lie in the visible region between 2.46 and 2.72 eV. Photoluminescence spectra show defects-free nature of synthesized nanorods. The hump of emission band, around 430 nm in Co-doped CdS nanorods, attributes to the direct transition from the energy states created in CdS. Magnetic study reflects the ferromagnetic character of synthesized nanorods with high magnetic saturation, 0.034, 0.041, 0.070 and 0.090 emu g−1 for, respectively, pure, 5%, 10% and 15% Co-doped CdS nanorods. The observed ferromagnetism in the synthesized nanorods have been explained on the basis of F-center (sulfur vacancy) mediated exchange mechanism and indirect interaction among Co (II) centers.