Peculiar magnetic properties of Fe/Ni multilayers on $Fe(001)$ - $p(1\times 1)$O by spin-resolved photoemission spectroscopies.

Goto F., Calloni A., Fratesi G., Albani G., Finazzi M., Duò L., Ciccacci F., Bussetti G.
  Martedì 13/09   09:00 - 13:30   Aula D - Marianna Ciccone   II - Fisica della materia   Presentazione
We present a structural and spectroscopic characterization of Ni and Fe multilayers grown on bcc Fe. The substrate is treated in order to form an oxygen superstructure, namely the Fe-{p(1\times $1)$O surface. The presence of an oxygen overlayer, capable of floating at the Ni/Fe sample surface even at room temperature, contributes to a peculiar morphological evolution and intervenes in the structural relaxation of the metastable Ni overlayer. We investigate the magnetic properties of the multilayer, at each step of the growth, by the combined use of $in situ$ spin-resolved photoemission spectroscopy (SR-PES) and inverse photoemission spectroscopy (SR-IPES). A strong decrease of the spin polarization is observed as the thickness of the bcc Ni layer increases, with a clear quenching of the magnetization at $6 {ML}$ of Ni. When iron is deposited on $6 {ML}$ Ni, there is an abrupt restoration of the spin polarization, even at one monolayer coverage, as also obtained from density functional theory (DFT) calculations. In addition, we observe the disappearance of a feature related to majority electrons above the Fermi level, directly linked to the presence of the underlying buffer layer.