Effects of oxygen-reducing atmosphere annealing on LaMnO3 epitaxial thin films

We investigated the effects of annealing on LaMnO3 epitaxial thin films grown by pulsed laser deposition (PLD) and propose an efficient method of characterizing their stoichiometry. Structural, magnetic and optical properties coherently indicate non-stoichiometric ferromagnetic and semiconducting phases for as-grown LaMnO3 films. By annealing in an oxygen-reducing atmosphere, we recovered the antiferromagnetic and insulating phases of bulk-like stoichiometric LaMnO3. We show that non-destructive optical spectroscopy at room temperature is one of the most convenient tools for identifying the phases of LaMnO3 films. Our results serve as a prerequisite for studying LaMnO3 based heterostructures grown by PLD.