Atomic scale growth of GdFeO3 perovskite thin films

Abstract

Thin films of multiferroic gadolinium orthoferrite (GdFeO3) are of significant interest due to intrinsic coupling of magnetic and ferroelectric order in their monolithic bimetallic structures relevant for potential applications in magneto-optical data storage devices. Formation of this composition in stoichiometric pure form is challenging due to facile formation of the thermodynamically preferred garnet phase (Gd3Fe5O12) that mostly coexists as a minor phase in gadolinium orthoferrite films. We report herein the selective epitaxial growth of GdFeO3 films by atomic layer deposition of a single bimetallic precursor [GdFe(OtBu)6(C5H5N)2] containing Gd:Fe in the required stoichiometric ratio, and using ozone as co-reactant. Intact vaporisation of [GdFe(OtBu)6(C5H5N)2] in the gas phase and its clean conversion into the complex oxide phase as validated by mass spectral studies and thermogravimetry demonstrate the potential of the Gd-Fe compound as an efficient single-source precursor. Epitaxial growth of GdFeO3 on SrTiO3 substrates was confirmed by X-ray diffraction analysis, whereas the presence of Fe3+ and Gd3+ without any traces of N species from the ligands was verified by X- ray photoelectron spectroscopy. Magnetic properties of the resulting perovskite films studied by superconducting quantum interference device measurements revealed the superposition of two independent magnetic contributions due to paramagnetic (Gd3+) and ferromagnetic (Fe3+) sublattices in GdFeO3.