Magnetic properties of Mn-doped ZnO powder and thin films

Zn0.96Mn0.04O powder and thin films were prepared by standard solid-state reaction processes and radio-frequency (RF) magnetron sputtering. Magnetic measurements indicate that the powder is paramagnetic for temperatures above 3 K, while the thin films annealed in vacuum are ferromagnetic at room temperature with a transition temperature of about 400 K. The largest saturated magnetization (Ms) was found to be about 1.05 μB/Mn, while the coercive force was found to be 100 Oe at room temperature. The very different results for the powder and thin films indicate that growth conditions and defects play an important role in producing ferromagnetism.