1. Ohno, H.: Making nonmagnetic semiconductors ferromagnetic. Sci. 281, 951–956 (1998)
2. Vijayaprasath, G., Murugan, R., Ravi, G., Mahalingam, T., Hayakawa, Y.: Characterization of dilute magnetic semiconducting transition metal doped ZnO thin films by sol–gel spin coating method. Appl. Surf. Sci. 313, 870–876 (2014)
3. Azab, A.A., Ateia, E.E., Esmail, S.A.: Comparative study on the physical properties of transition metal- doped (Co, Ni, Fe, and Mn) ZnO nanoparticles. Appl. Phys. A. 124(469), (2018)
4. Khan, R.Z., Araujo, C.I.L., Khan, T., Rahman, M.U., Rehman, Z.U., Khan, A., Ullah, B., Fashu, S.: Influence of oxygen vacancies on the structural, dielectric, and magnetic properties of (Mn, Co) Co-doped ZnO nanostructures. J. Mater. Sci: Mater. El. 29, 9785–9795 (2018)
5. Franco Jr., A., Pessoni, H.V.S., Ribeiro, P.R.T., Machado, F.L.A.: Magnetic properties of Co-doped ZnO nanoparticles. J. Magn. Magn. Mater. 426, 347–350 (2017)