http://www.cnr.it/ontology/cnr/individuo/prodotto/ID252489
Circular dichroic experiments with electrons - recent results of the CHIRALTEM project (Contributo in atti di convegno)
- Type
- Label
- Circular dichroic experiments with electrons - recent results of the CHIRALTEM project (Contributo in atti di convegno) (literal)
- Anno
- 2005-01-01T00:00:00+01:00 (literal)
- Alternative label
P. Schattschneider, S. Rubino, C. Hébert, E. Carlino, M. Fabrizioli, P. Formanek, H. Lichte, J. Zweck, C. Hurm, P. Novak, J. Rusz: (2005)
Circular dichroic experiments with electrons - recent results of the CHIRALTEM project
in EDGE 2005 EELS-Workshop, Grundlsee (Austria), 1. - 5.5.2005
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- P. Schattschneider, S. Rubino, C. Hébert, E. Carlino, M. Fabrizioli, P. Formanek, H. Lichte, J. Zweck, C. Hurm, P. Novak, J. Rusz: (literal)
- Rivista
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- LMSSMat, CNRS-UMR 8579, Ecole Centrale Paris, Châtenay-Malabry, France
Institute for Solid State Physics, Vienna University of Technology, Vienna, Austria
TASC-INFM National Laboratory, I-34012 Trieste, Italy
Institute of Physics, Academy of Sciences, Prague, Czech Republic
Institute for Magnetism and Magnetoelectronics, University of Regensburg
Institute of Structure Physics, University Dresden, Germany (literal)
- Titolo
- Circular dichroic experiments with electrons - recent results of the CHIRALTEM project (literal)
- Abstract
- The recent progress in instrumentation guarantees that ELNES will rest a strong
competitor of XANES in spite of the improved spatial resolution seen with
synchrotrons. Up to now there was however one application uniquely reserved for
synchrotrons: X-ray magnetic circular dichroism (XMCD). Recently it was shown
that contrary to intuition XMCD can well be measured with inelastic electron
scattering [1]. In analogy to XMCD we introduced the term ELMCD: Energy Loss
Magnetic Chiral Dichroism. We choose the adjective chiral instead of circular in order
to stress that there is no (circular) polarization of the probe electron involved. Rather,
it is the chirality of the allowed transitions that is detected in the inelastic electron
scattering experiment.
In the experiment, a coherent superposition of two momentum transfer vectors
perpendicular to each other is set up, tuning the phase difference between the two
interactions to p/2. The inelastic interference term carries then the dichroic signature.
The proper tool for description of inelastic interference, and as such also for ELMCD
is the mixed dynamic form factor (MDFF). More precisely, it turns out that the
signature of ELMCD is contained in the imaginary part of the MDFF. In the dipole
approximation, a particularly simple expression is obtained.
An overview of the present situation of the CHIRALTEM project is given, including
several possible experimental setups to measure the dichroic signal with electrons
(Bloch wave interferometry, biprism in the C2-aperture, and double crystal
interferometry). We report also on attempts to manipulate the magnetic field in the
specimen by a dedicated holder, as is needed for ELMCD. Simulation of the Ni and
Fe ELMCD based on a modified version of the WIEN2k package are discussed.
We present also the first successful comparison of ELMCD with XMCD, obtained in
a TEM and in a synchrotron, performed with the same specimen.
References
[1] C. Hébert, P. Schattschneider, Ultramicroscopy 96 (2003) 463.
[2] This research was supported by the European Commission, contract nr.
508971 (CHIRALTEM). (literal)
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