Turning Insulators into Metals
Professor Stuart S. P. Parkin
The science of spintronic materials, magnetic thin films and metallic conductors play a major role in Argonne's pursuit to develop advanced materials, methods and technologies that will accelerate and sustain scientific breakthroughs in multiple fields and disciplines.
To continue the laboratory's scientific excellence in creation, development and maturation of next generation science and technology Stuart S. P. Parkin has been invited to present "Turning Insulators into Metals" at a Director's Special Colloquium on Friday, August 2, 11 a.m., at the TCS Conference Center in Building 240.
As a visionary experimental physicist he has stretched the scientific boundaries of magnetic thin-films. At IBM he developed the spin valve which allowed for a 1,000-fold increase in magnetic hard disk drive data density.
He has authored or co-authored more than 420 papers
and holds more than 95 issued patents.
He has received numerous fellowships, mostly notably being named a fellow of the Royal Society of London and the American Academy of Arts and Sciences. He is a member of the National Academy of Sciences and the National Academy of Engineering.
Parkin’s research interests have included organic superconductors, high-temperature superconductors, and most recently, magnetic thin film structures, spintronic materials and devices for advanced sensor, memory and logic applications.
Parkin currently is the manager of the Magnetoelectronics group at the IBM Almaden Research Center, a consulting professor in the Department of Applied Physics at Stanford University and director of the IBM-Stanford Spintronic Science and Applications Center.
The electric field induced metallization of insulating oxides is a powerful means of exploring and creating novel electronic states. Recently large internal electric fields from polar surfaces have been used to create emergent metallic, superconducting and magnetic states at interfaces between two insulating oxides. However, the origin of the metallicity is a subject of considerable debate, especially as to whether charged carriers are induced electrostatically. We show that by placing various oxide surfaces and thin films in contact with charged fluids, these nominally insulating materials can be transformed into metallic conductors and that the mechanism is rather due to the flow of ionic currents of oxygen to and fro between the oxide surface and the liquid.
We discuss, in particular, the electrolyte gating of epitaxial films of vanadium dioxide (VO2). VO2 exhibits a transition from an insulating to a metallic state above a metal-insulator transition temperature, TMIT, that depends on strain induced in the film by epitaxy with underlayers and/or the substrate material and crystal orientation. Using in-situ gating we use x-ray diffraction to show that the out-of-plane lattice constant can be reversibly changed by more than 3.5% using ionic liquid gating. The possibility of novel, highly energy efficient “liquid” electronics is discussed.
 J. Jeong, N. Aetukuri, T. Graf, T. D. Schladt, M. G. Samant, and S. S. P. Parkin, Science 339, 1402 (2013).