Growth and characterization of nonpolar, heavily Mn-substituted ZnO films

Abstract

Eight percent of Mn was successfully diluted into nonpolar ZnO films deposited by pulsed laser deposition on single crystal (100) SrTiO3 substrates. X-ray diffraction patterns and energy-dispersive X-ray spectroscopy confirmed high crystallinity of the films and excluded unintentional magnetic doping. A unique surface domain structure was observed by scanning electron microscope and atomic force microscope, which might play a vital role to strain release induced by lattice mismatch between nonpolar (11-20) ZnO film and (100) SrTiO3 substrate. In addition, the films showed strong ferromagnetism with a large coercivity HC ∼180Oe at room temperature. The large magnetic moment is ascribed to carrier-mediated exchange interaction between the Mn ions, where the majority of the carriers are oxygen vacancies.