Magnetic and optical properties of Zn1−xMnxO thin films prepared by pulsed laser deposition

We report on ferromagnetic characteristics of Zn1−xMnxO thin films grown on Al2O3 substrates by using pulsed laser deposition. The effects of oxygen pressure on the ferromagnetism in the Mn-doped ZnO thin films are discussed. The carrier concentration was found to be controlled by varying the oxygen pressure. By decreasing oxygen pressure, the films exhibited increases in both the lattice constant and fundamental band gap energy. Large magnetoresistance (MR) was observed in the film grown at 700 °C, especially over 10% in the positive MR. The results indicate the spin splitting caused by strong s-d exchange coupling between the conducting carriers and localized spins of Mn ions.