Epitaxial growth of γ-Fe2O3 thin films on MgO substrates by pulsed laser deposition and their properties

Epitaxial γ-Fe2O3 films were fabricated by pulsed laser deposition at 350 °C in an oxygen-rich atmosphere onto a (0 0 1) or (1 1 0) MgO substrate utilizing the substrate template effect, while the corundum structure α-Fe2O3 was obtained when the same experiment was conducted using sapphire or quartz substrate. X-ray photoelectron spectroscopy analysis and low-temperature SQUID measurements confirmed the formation of γ-Fe2O3. After annealing at 500 °C for 1 h under oxygen atmosphere, the γ-Fe2O3 phase was still maintained. The saturation magnetization (Ms) of the γ-Fe2O3 film was around 400 emu cm−3 for films 10–50 nm thick, which is in agreement with the bulk value. The ultrathin films showed an enhanced Ms value (489 emu cm−3). In particular, the Ms of the 5 nm thin film did not diminish even if it was subjected to high-temperature annealing due to the stabilizing effect of the epitaxial growth. The thin films obtained had a flat surface, which is desired for spin filter and other applications.