Epitaxial Growth of Orthorhombic GaFeO₃ Thin Films on SrTiO₃ (111) Substrates by Simple Sol-Gel Method.

A Sol-gel method assisted with spin-coating has been successfully used to grow orthorhombic GaFeO3 epitaxial films on SrTiO3 (111) substrates for the first time. The film with Pna2(1) crystal structure has been grown along the c-axis. The rocking curve of (004) reflection shows that the Full-Width at Half-Maximum (FWHM) value could be determined to be 0.230 degrees, indicating good single crystallinity and high quality. X-ray phi scan reveals a three-fold symmetry of the substrate and a six-fold symmetry of the film, respectively. The in-plane domains rotate 60 degrees from each other in the film. Uniform film with dense structure, columnar grains with similar grain size was obtained. The thickness of the film was evaluated to be 170 nm. The roughness value (RMS) measured by AFM was 4.5 nm, revealing a flat film. The in-plane Magnetization versus Magnetic field (M-H) curve at 5 K performs a typical ferri- or ferromagnetic hysteresis loop with a saturated magnetization (M-s) value of 136 emu/cm(3). The Curie temperature could be determined to be 174 K. Compared to Pulsed Laser Deposition (PLD), the sol-gel method can prepare large area films with low cost. These new films show promising applications in multiferroic devices.