Data di Pubblicazione:
2012
Citazione:
Theory and first principle calculation of CVV Auger spectra of magnetic systems / G. Fratesi, M.I. Trioni, G.P. Brivio. ((Intervento presentato al convegno Magnetic order in nanostructures and spectroscopy tenutosi a Roma nel 2012.
Abstract:
We present the progress of the Milano-Bicocca PRIN [1] Research
Unit (RU), where a numerical code for the calculation of
spin-polarized, angle-resolved core-valence-valence Auger
spectra was developed and applied to bulk and surface magnetic
systems.
The spin polarization of the emitted electrons from 3d
impurities in simple metal hosts in a core-valence-valence
Auger process is analyzed in terms of a first-principles
density-functional theory approach, by using the golden rule.
The relationship between the spin-dependent local density of
states, the magnetic moments of the 3d atoms and the
energy-dependent and total spin polarization of the Auger
electrons is discussed. It is shown how to estimate the
magnetic moment of the impurities from a measure of the total
spin polarization of the Auger electrons. This can be achieved
considering (i) that the Auger signal is simply due to the
impurities only, (ii) the very locality of the Auger
phenomenon, and (iii) a simple and general relationship between
the spin polarization and the magnetic moment of the impurity
which we show to be independent of the metal host.
Spin selectivity in angle-resolved Auger photoelectron
coincidence spectroscopy (AR-APECS) is used to probe electron
correlation in ferromagnetic thin films measured by the RUs of
RomaTre and Trieste. In particular, exploiting the AR- APECS
capability to discriminate Auger electron emission events
characterized by valence hole pairs created either in the high
or in the low total spin state, a strong correlation effect in
the MVV Auger lineshape of Fe/Cu(001) thin films was detected.
Theoretical simulations allow one to ascribe this effect to
interactions within the majority spin sub band. Such an
assignment follows from a close comparison of the experimental
AR-APECS lineshapes with the predictions of a model based on
spin polarized density functional theory and the Cini-Sawatzky
approach.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
G. Fratesi, M.I. Trioni, G.P. Brivio
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