Stabilization of Epitaxial α-Fe2O3 Thin Films Grown by Pulsed Laser Deposition on Oxide Substrates

We have grown epitaxial incommensurate α-Fe2O3 thin films on α-Al2O3(0001), SrTiO3(111) and LaAlO3(001) substrates, identifying hematite as single iron oxide phase stabilized. We demonstrate that a different lattice coupling behavior as a function of the selected oxide substrate mediates the epitaxial character. Single oriented α-Fe2O3(0001) layers are obtained on α-Al2O3(0001) and SrTiO3(111) substrates whereas on LaAlO3(001) substrate the hematite layer is found to grow along the r-plane in order to adapt its hexagonal lattice on the cubic lattice of substrate, evidencing a single oriented (11 02) layer. In the film plane, crystallographic axes of α-Fe2O3(0001) are collinear with the α-Al2O3(001) ones while a rotation of 30o is found between those of α-Fe2O3(0001) and SrTiO3(111). On LaAlO3(001), α-Fe2O3(11 02) adopts an in-plane orthorhombic structure rotated 45o respect to the substrate lattice. The crystallographic domain size and crystalline order are dependent on the incommensurate lattice coupli...