Room-temperature ferromagnetism in Co-doped ZnO thin films prepared by sol-gel method

We report on room-temperature ferromagnetism in Co-doped ZnO thin films grown onto Si(100) and SiO2 substrates using the spin-coating technique. X-ray diffraction measurements show that the films have the wurtzite structure with a preferential orientation along the c-axis. UV-Visible spectroscopy has shown that the Co2+ ions are substituted to Zn2+ ions in ZnO matrix. The analysis of the magnetization measurements indicates that the observed ferromagnetism in ZnO and Co-doped ZnO films is extrinsic and can be due to a pollution