Woodruff School of Mechanical Engineering



Full field electron spectromicroscopy for surface imaging of ferroic interfaces


Dr. Nick Barrett


Universite Paris Saclay


Thursday, April 11, 2019 at 2:30:00 PM


MRDC Building, Room 3515


Dr. Nazanin Bassiri-Gharb


For many applications in electronics, the surface or interface is key. Domain walls (DWs) are interfaces that break translational symmetry to exhibit astonishing and very different properties compared to their parent materials, including superconductivity, magnetism and polarity. Intrinsically 2D objects with a thickness of a few unit cells, DWs represent a new paradigm for material as the machine. As such, they could become a novel paradigm for post-CMOS electronic devices, where the interface is the active element. This talk will present two studies of DWs: polar twins and dipole moments at ferroelastic CaTiO3 surfaces, and surface domain structure above the Curie temperature in BaTiO3. These studies leverage advanced low energy electron optics, which have transformed photoemission electron microscopy (PEEM) and low energy electron microscopy (LEEM) into techniques capable of revealing surface charge, polarity, topography, chemistry and band structure.


Dr. Nicholas Barrett received his PhD in Applied Physics from the University of Strathclyde (Scotland) in 1987. He joined the CEA in 1990 and in 1996 became beamline manager at the SuperACO-LURE synchrotron. In 2005, he obtained the Habilitation à Diriger des Recherches from the University Pierre and Marie Curie of Paris VI. He is currently a senior researcher at CEA/IRAMIS/SPEC and is involved in many national and European projects as coordinator or partner. He is an expert in photoelectron spectroscopy using synchrotron radiation, ultra-fast laser and laboratory sources. Recent work has included correlation between interface chemistry, electronic structure and device performance in ultra-thin capacitor structures, domain dynamics during structural phase transitions and electronic structure of microscopic single domain graphene flakes. He is author of 150 scientific papers, and the coordinator of the European Union funded collaborative project 3 Ferro working on ferroelectric hafnia-based oxides for low power consumption memory cells.