Ferromagnetism in carbon-doped thin films

Carbon-doped In2O3 thin films exhibiting ferromagnetism at room temperature were prepared on Si (100) substrates by the rf-magnetron co-sputtering technique. The effects of carbon concentration as well as oxygen atmosphere on the ferromagnetic property of the thin films were investigated. The saturated magnetizations of thin films varied from 1.23 to 4.86 emu/cm3 with different carbon concentrations. The ferromagnetic signal was found stronger in samples with higher oxygen vacancy concentrations. In addition, deposition temperature and different types of substrates also affect the ferromagnetic properties of carbon-doped In2O3 thin films. This may be related to the oxygen vacancies in the thin film system. The experiment suggests that oxygen vacancies play an important role in introducing ferromagnetism in thin films.