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SUMMARY:Phase contrast/retrieval as a quantitative link to the physics of 
 nano-materials - Marco Beleggia\, University of Leeds and Brookhaven Natio
 nal Labs\, U.S.
DTSTART:20080219T150000Z
DTEND:20080219T160000Z
UID:TALK9924@talks.cam.ac.uk
CONTACT:Dr Jonathan Barnard
DESCRIPTION:The phase of electrons contains a wealth of information on the
  physics of nanomaterials. In addition to spatial high-resolution\, typica
 l of modern Transmission Electron Microscopy\, the sensitivity of electron
 s to electromagnetic fields generated by nanostructures of interests enabl
 es us to establish a quantitative link between the retrieved signal and th
 e\nproperties of magnetic (and electronic) materials at the nanoscale. Suc
 h link\, and its benefits in terms of gained knowledge\, will be illustrat
 ed while exploring magnetic phase diagrams of shape-controlled nanostructu
 red arrays: from the basic physics governing the magnetic response and hys
 teretic properties\, configurational models are developed as a function of
  shape\, geometry\, composition\, and other external parameters\; the elec
 tron-optical phase shift is then evaluated and compared with the signal re
 trieved from holography experiments\; the goal is to establish a quantitat
 ive framework where the expected magnetic ground state is determined univo
 cally. In this perspective\, the key element is a computational strategy d
 eveloped recently that relies on the reciprocal representation of the phys
 ical quantities (fields and potentials) responsible for phase-shifting the
  electron beam.
LOCATION:T001 [Tower Seminar Room]\, Materials Science and Metallurgy\, De
 partment of
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