Divine Phillip Kumah
Department of Physics,
North Carolina State University
Manipulating Electronic and Magnetic Phases at Complex-Oxide Interfaces
Location: EB1 Room 1011
Friday, April 28th 2017 - 11:00 am
Complex oxide materials provide a wide range of unique electronic, orbital and magnetic properties which are intimately linked to their atomic scale structure. The ability to form heterostructures comprising of atomic layers of different oxide materials with differing properties has led to the realization of emergent phenomena including multiferroicity, high mobility two dimensional electron gases and superconductivity which are not found in the constituent materials. A key research question relates to understanding the origin of these interface-induced phenomena. Using high-resolution synchrotron diffraction to image the interfacial structures of oxide heterostructures, we show that structural distortions driven by interfacial polar distortions significantly affect their electronic, orbital and magnetic properties. This talk will focus on rare-earth nickelate and manganite thin films where observed structural distortions affecting the transition metal-oxygen bond lead to metal-insulator and magnetic transitions. Novel approaches will be presented to control atomic distortions and engineer the electronic, orbital and magnetic properties of these systems.
Divine Kumah received his Ph.D in Applied Physics from the University of Michigan in 2009 and did postdoctoral research at the Center for Research in Interface and Surface Phenomena at Yale University. His research interests are in experimental condensed matter physics and are aimed at understanding the novel properties which emerge at the interfaces between crystalline materials. The Kumah Research Group at NC State uses state of the art atomic layer-by-layer deposition techniques including molecular beam epitaxy to fabricate thin crystalline oxide films. The group is focused on understanding how atomic-scale structural distortions at interfaces can be manipulated to induce novel electronic and magnetic phenomena and the development of pathways for harnessing these unique functionalities for electronic and energy applications. Tools used by the group include atomic force microscopy, electron diffraction and synchrotron-based x-ray spectroscopy and diffraction.