An Atomic Structure Based Approach to Realizing Novel Properties in Oxide Heterostructures
Speaker: Steven J. May, Drexel U.
Date & Time: September 6, 2012 - 12:00pm
Location: Chem. 260
Scientific interest in ABO3 perovskite oxides remains intense due to the wide range of physical behavior present in these materials. Recent advances in thin film deposition techniques, such as molecular beam epitaxy, have made it possible to synthesize perovskite heterostructures and superlattices with unit cell precision. This talk will focus on how the formation of oxide heterostructures can be used to stabilize non-equilibrium atomic structures in perovskites, thereby leading to novel electronic and magnetic properties. In the first half, I will describe how the arrangement of the A- and B-site cations can be controlled to achieve novel cation-ordered structures. As an example, the observation of enhanced long-range antiferromagnetic order and spatially confined ferromagnetism in (LaMnO3)n/(SrMnO3)m superlattices will be presented. In the second half, I will discuss how the position of the oxygen anions can be controlled to stabilize non-equilibrium bond angles and lengths, thereby altering electronic bandwidth. The experimentally measured response of the BO6 octahedra to epitaxial strain and superlattice formation in LaNiO3-based heterostructures will be described. The structural results will be compared with electronic transport properties to elucidate how strain alters conductivity in nickelate films.
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