MSE Colloqium: Julia Mundy, Ferroic engineering of atomic layers to create a room-temperature multiferroic

Abstract

Transition metal oxides exhibit almost every physical state known including metallic conductivity, (high-temperature) superconductivity, colossal magnetoresistance, photoconductivity, ferroelectricity, and ferromagnetism.  Key to both harnessing these exotic phases in device applications and further materials discovery is developing an atomic-resolution understanding of the structural, electronic and magnetic properties.  Here I will show how analytical electron microscopy and spectroscopy, in conjunction with advanced thin film deposition, can be used to engineer new materials including a magnetoelectric multiferroic superlattice where ferroelectricity enhances magnetism at all relevant length scales.  Starting with a single layer of a ferrimagnet with magnetic spin frustration, we impose sub-Angstrom ferroelectric rumpling to lower the spin frustration and boost the magnetic transition to above room-temperature.  As motivated by atomic-resolution electron spectroscopy, we further engineer the ferroelectric domain architecture to move charge through the system to boost the magnetic moment.  Our results demonstrate a design methodology for creating higher-temperature multiferroics by exploiting a combination of geometric frustration, polarization doping and epitaxial engineering.

Bio

Julia A. Mundy is a President's Postdoctoral Fellow in the Department of Materials Science and Engineering at the University of California, Berkeley.  Her research uses advanced thin film deposition and electron microscopy to design, synthesize and characterize complex oxide heterostructures with sub-Angstrom resolution.  Julia earned a B.A. in Chemistry and Physics and an M.A. in Chemistry from Harvard University and a PhD in Applied Physics from Cornell University where she was a National Science Foundation and National Defense Science and Engineering Graduate Fellow.  She has also been recognized by the Materials Research Society, the American Physical Society/American Institute of Physics and the Microbeam Analysis Society.