Abstract
A range of insulating double perovskite materials were investigated for use as buffer layer materials on which to grow the half metallic, magnetoresistive Sr2FeMoO6. Chosen for their closely matching lattice parameters Sr2AlXGa1-XTaO6, Sr2CrNbO6, and Sr2NiWO6 have been grown by PLD. All buffer materials have been characterized by XRD, AFM, and RBS. Critical film growth parameters have been optimized to produce smooth, pure phase buffer films. SFMO has been deposited on each buffer layer and its magnetic properties have been measured. Buffer layer parameters of growth orientation, growth interface roughness, lattice mismatch, and stoichiometry have been analyzed. STEM HAADF images were collected from select samples to verify the interface sharpness and possible defects contributing to the magnetic signal. Improved magnetic properties of buffer layer-SFMO films grown in the (001) orientation are shown to be the result of decreased surface roughness and minimal lattice mismatch between the buffer layer and SFMO. Growth could not be improved using buffer layers when SFMO was grown in the (111) orientation because of processing limitations and the need for atomically sharp interfaces. In response, initial single crystal growth experiments of the buffer material Sr2NiWO6 have been completed. Challenges to this and other complex oxide single crystal growth will be discussed.
Bio
Alexanne Holcombe Johnson has a B.S. from Otterbein College in Chemistry. She works for Dr. Patricia Morris on complex oxide film and crystal growth. She works with an interdisciplinary team of researchers as part of the Center for Emergent Material (CEM), to investigate the unique properties and processing issues of double perovskite materials