|Atomic spin state selectivity in Auger Photo Electron Coincidence Spectroscopy (APECS): a tool for the investigation of local magnetism |
Laboratory for Surface Modification
|Giovanni Stefani, CNISM and Dipartimento di Fisica Universita’ Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy)|
12:00 Noon, Chem 260
Recently, Auger line shape studied by Auger Photoelectron Coincidence Spectroscopy (APECS) has been demonstrated to possess a final state selectivity  that provides chemical state, local environment and emission depth sensitivity . By detecting the Auger-photoelectron pair with moderate angle selectivity, contribution from spin-symmetric (triplet) and spin-antisymmetric (singlet) final states can be selectively enhanced or suppressed. Hence, a new method for investigating the spin state of solid surfaces is provided. This Dichroic Effect in APECS (DEAR-APECS) has been proposed as a probe of the local valence electronic structure with element, chemical states, emission depth, and spin selectivity . By means of the spin final state selec-tivity embedded in the DEAR effect, a sizable magnetic dichroism in the Auger lineshapes is achieved. In the simplest approach dichroism can be explained in terms of conditioned convolutions of the majority and minority densities of states, possibly corrected by a Cini –Sawatzky model to account for spin dependent correlation effects. APECS is thus proposed as a new promising tool for the investigation of local magnetism in systems that are structured on the nanometer scale.
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