Evidence of room temperature ferromagnetism in Co-doped transparent CuAlO2 semiconductor

Highlights: ► Co-doped CuAlO2 semiconductors were successfully synthesized by solid state reaction. ► Proper EC and terpineol solvent were helpful for CuAlO2 thin films deposition by spin-on technique. ► We investigated RT diamagnetism for pristine CuAlO2 and ferromagnetism for Co-doped CuAlO2. ► The RT ferromagnetism altered with Co content from 1 at. % to 7 at. %. - Abstract: We synthesized CuAl1−xCoxO2 (x = 0.00–0.07) thin films by solid-state reaction from Cu2O and Al2O3 on a sapphire (0 0 1) substrate by a simple and cost-effective spin-on technique. X-ray diffraction and Raman spectroscopy confirm the formation of single impurity-free delafossite CuAlO2 structure for all the compositions. We observed diamagnetism for pristine CuAlO2 and ferromagnetism for Co-doped CuAlO2 at room temperature. Specially, the coercivity (Hc) and saturation magnetization (Ms) are significantly enhanced with Co composition from 1 at.% to 5 at.% but show the reverse tendency with higher Co content.