Public Physic Colloquium in the Summer Terms 2012 in Münster
Place:     Germany, 48149 Münster, Wilhelm-Klemm-Str. 10, IG I, HS 2
Time:     Thursday, 05.07.2012  16:00 h c.t.
Colloquium Coffee at 15:45 h  at the Lecture Hall

New opportunities for imaging magnetic fields and electrostatic potentials in materials in the transmission electron microscope
Prof. Dr. Rafal Dunin-Borkowski, Forschungszentrum Jülich, Institute for Microstructure Research, Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institue

In this talk, I will describe recent developments in the application of off-axis electron holography and Lorentz transmission electron microscopy to the characterisation of magnetic fields and electrostatic potentials in nanoscale materials, minerals and devices examined as a function of temperature and applied bias in situ in the electron microscope. I will begin by presenting results obtained from extended crystals and nanoparticles of magnetite (Fe₃O₄) examined below the Verwey transition, at which the magnetocrystalline anisotropy increases by an order of magnitude and the magnetic easy axis switches from the <111> directions of the parent cubic phase to the [001] direction of the low temperature monoclinic phase. I will then present measurements of magnetic states and switching mechanisms in two-dimensional arrangements of sub-50-nm nanocrystals and discuss prospects for the quantitative measurement of weak and three-dimensional magnetic fields and local charge densities in materials from electron-optical phase images. I will conclude by showing initial results obtained from a chromatic aberration correction transmission electron microscope, which promises to allow images to be recorded in magnetic-field-free conditions with close to atomic spatial resolution.

Invited from: Prof. Dr. H. Kohl

By Order of the Professors of the Department of Physics

Prof. Dr. Sergej Demokritov