Defect-induced magnetic order in pure ZnO films


Defect-induced magnetic order in pure ZnO films

Khalid, M.; Ziese, M.; Setzer, A.; Esquinazi, P.; Lorenz, M.; Hochmuth, H.; Grundmann, M.; Brauer, G.; Anwand, W.; Fischer, G.; Adeagbo, W. A.; Hergert, W.; Ernst, A.

We have investigated the magnetic properties of pure ZnO thin films grown under N2 pressure on a-, c- and r-plane Al2O3 substrates by pulsed laser deposition. The substrate temperature and the N2 pressure were varied from room temperature to 570 °C and from 0.007 mbar to 1.0 mbar, respectively. The magnetic properties of bare substrates and ZnO films were investigated by SQUID magnetometry. ZnO films grown on c- and a-plane Al2O3 substrates did not show significant ferromagnetism. However, ZnO films grown on r-plane Al2O3 showed reproducible ferromagnetism at 300 K when grown at 300¡400 °C and 0.1-1.0 mbar N2 pressure. Positron annihilation spectroscopy measurements as well as density functional theory calculations suggest that the ferromagnetism in ZnO films is related to Zn vacancies.

  • Physical Review B 80(2009), 035331

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Publ.-Id: 12969