Understanding of local magnetism and electron correlation of NiO/Ag(001) and Ni/Cu(001) by AR-APECS

Angle resolved Auger photoelectron coincidence spectroscopy (AR-APECS) is able to distinguish contribution from different final spin states to the Auger intensity. ARAPECS measurements have been carried out below and above the magnetic transition temperature for antiferromagnetic NiO/Ag(001) and ferromagnetic Ni/Cu(001), at the ALOISA beamline at the Elettra synchrotron in Trieste. The presence of antiferromagnetism in NiO/Ag has been confirmed by observing dichroism in x-ray absorption spectra, while ferromagnetism in Ni/Cu has been monitored off-line by MOKE measurements as a function of temperature and film thickness. AR-APECS measurements of NiO/Ag in the antiferromagnetic state display a huge dichroism which disentangles singlet, triplet and quintet contribution from M23M45M45 Ni Auger intensity and which completely disappears above the Néèl temperature. ARAPECS measurements of ferromagnetic Ni/Cu present a more complex behavior where a quasi atomic-like line shape changes when crossing the magnetic transition as a function of the temperature as well as a function of the thickness.