Combination of Chemical and Physical Methods to Produce High-Quality Epitaxial Zn1−xMnxO Thin Films

We have carefully analyzed the epitaxial growth and magnetic properties of Zn1−x Mn x O (x=0–0.1) thin films fabricated by pulsed laser deposition on c-Al2O3(0001) substrates. The ablation targets are prepared by pressing nano-sized Zn1−x Mn x O (x=0–0.1) powders which were previously synthesized by the polymeric precursor method. The films show excellent crystalline quality with full width at half-maximums varying from ∼0.07–1∘. Some films show well-defined magnetic hysteresis loops both at 300 and 5 K, which suggests the presence of ferromagnetic order. Nevertheless, we find that the ferromagnetism in the samples depends strongly on the oxygen partial pressure in the deposition chamber. This finding suggests that the observed ferromagnetism in Mn-doped ZnO is not an extrinsic property of the system. It is probable that unpaired electron spins, which have their origin in the oxygen vacancies, are responsible for the observed ferromagnetic behavior.