LaMnO_3 Thin Films Grown by Using Pulsed Laser Deposition and Their Simple Recovery to a Stoichiometric Phase by Annealing

We systematically investigated various physical properties of epitaxial LaMnO_3 thin films fabricated on SrTiO_3 substrate by using pulsed laser deposition. In particular, we observed drastic changes in their properties when the as-grown films were annealed in a reduced-oxygen atmosphere. Whereas the as-grown LaMnO_3 film showed ferromagnetic and semiconducting properties with a small optical band gap, the LaMnO_3 films annealed at temperature higher than 700 ℃ showed antiferromagnetic and insulating properties with an enlarged band gap. The optical features also changed drastically, in that the optical transition peak shifted to a higher energy with additional fine structures. Such changes were made in a direction such that the LaMnO_3 films were more stoichiometric, indicating that the stoichiometric phase could be recovered by simple annealing of the pulsed-laser-deposited films. Finally, possibilities of the polar catastrophe scenario at the interface between LaMnO_3 and SrTiO_3 are briefly discussed. KCI Citation Count: 14