Microstructure and physical properties of ε-Fe2O3 thin films fabricated by pulsed laser deposition

epsilon-Fe2O3 has attracted intense interest in the field of magnetoelectric materials due to its promising physical properties. The epitaxial growth of epsilon-Fe2O3 thin films is challenging since it is a metastable phase of iron oxide. In this study, epsilon-Fe2O3 (001) thin films are epitaxially grown on SrTiO3 (111) substrates by pulsed laser deposition (PLD). The crystal structure, valence state, and microstructure of the epsilon-Fe2O3 thin films are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. It is revealed that the oxygen pressure, deposition and annealing temperatures, and laser beam energy affect significantly the epitaxial growth of epsilon-Fe2O3 thin films. The orientation relationship between films and substrates is epsilon-Fe2O3 (001)[010] // SrTiO3 (111)[(1) over bar 10]. The magnetic hysteresis loops tested by a superconducting quantum interference device and UV-Vis reflection spectra suggest that the epsilon-Fe2O3 thin film with thickness of similar to 20 nm has a strong magnetic anisotropy, a coercivity of 600 Oe, and an indirect band gap of 3.26 eV.