Abtract:Using Disorder or Liquid Electrolyte Gating to Design and Control Magnetic and Electronic Properties of Materials
Dr Julie Karel / Department of Materials Science and Engineering, Monash University, Clayton, Victoria, Australia
Many research efforts in condensed matter physics and materials science are directed towards developing methods to modify or realize novel materials properties. Some effective tools for doing this include introduction of disorder and application of electric fields; I will highlight examples of these from my own work during this talk. First, I will show that application of an electric field through a liquid electrolyte gate produces significant, non-volatile and reversible modifications in the electronic structure of transition metal oxides. More specifically, I will explain the origin of the low temperature metallicity in VO2 and WO3 thin films after liquid electrolyte gating and offer perspectives for this technique to initiate seemingly contradictory materials properties such as a polar metal. The second part of the talk will demonstrate that disorder can be used to effectively tune the magnetic and electronic properties in FexSi1-x and Fe1-yCoySi thin films; amorphous thin films exhibit an enhanced magnetic moment, enhanced spin polarization and large anomalous Hall effect in comparison to the crystalline material with the same composition. The talk will focus in particular on understanding the origin of the large AHE, which will be shown to depend primarily on the intrinsic mechanism (e.g. an electronic structure effect). This result is surprising because it indicates a local atomic level description of a Berry phase in a system that lacks lattice periodicity. Finally, I will discuss potential applications for amorphous materials in emerging electronic and spintronic devices.
About the speaker
Dr. Julie Karel earned her B.S in Materials Science and Engineering (MSE) from the University of Wisconsin – Madison (2005). From 2005-2007, Julie worked as a Materials Engineer for Intel Corporation in Santa Clara, CA and Chandler, AZ. Dr. Karel then obtained her M.S. (2010) and PhD (2012) also in MSE from the University of California – Berkeley. Her postdoctoral research was carried out at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany (2012-2016). Julie started as a research fellow at Monash University in late 2016 and has been a Lecturer in Materials Science and Engineering since 2018.