Tuning of multiferroic orders correlated to oxygen stoichiometry in magnetite films

Magnetite films are grown on Si(100) substrate using pulsed laser deposition technique. The deposition is performed at three fixed oxygen pressures of 0.4 × 10−6, 4.0 × 10−6, and 10 × 10−6 Torr keeping other conditions fixed. Raman and x-ray photoemission spectroscopies confirm formation of single magnetite phase for the first two pressures and a mixed phase composed of magnetite and hematite for the highest pressure. A trivial change in oxygen stoichiometry of magnetite is found crucial for the multiferroic orders at room temperature and below the charge ordering temperature. Possible mechanisms of multiferroic orders driven by change in oxygen stoichiometry are discussed.