Angular-dependent resonant-photoemission processes at the2pthresholds in nickel metal

Abstract

Angle-resolved valence-band resonant-photoemission of nickel metal has been measured close to the 2p core-level thresholds with synchrotron radiation. The well-known 6-eV correlation satellite has an intensity enhancement of about two orders of magnitude at resonance. The angular dependence of the photoemission intensity has been studied as function of photon energy and provides unambiguous evidence for interference effects all the way up to the resonance maximum. The observation of different angular asymmetries, ␤, for the valence band and the satellite is discussed in connection to the origin of the resonant-photoemission process and the character of the satellite.

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

“…4(c)), which is different for the two spin channels. The massive enhancement of the signal observed here does not imply strong interference effects: an analysis of the different contributions in the amplitude reveals that, in our case, the enhancement is given essentially by the resonant excitation alone, as was also found in other cases [8].…”

“…Such spectroscopies probe respectively the radiative and non radiative autoionization decay of a core hole, and the signal can be strongly enhanced with respect to the non resonant mode. The element and orbital selectivity of core level resonant spectroscopies allows to access higher order multipoles which are left unexplored by MCD in X-ray absorption (XAS) [1][2][3][4][5][6], to distinguish and enhance specific electronic excitations and satellites [7,8], collective magnetic excitations [9], ultrafast and charge transfer dynamics [10][11][12] and to detect quadrupolar transitions towards localized empty states [13,14]. In particular, RPES has recently been applied to several correlated materials [15][16][17][18][19] and full two dimensional angular scans of resonantly emitted electrons in moderately correlated materials have also been carried out [20,21].…”

Crystallization characteristics and chemical bonding properties of nickel carbide thin film nanocomposites

“…For x =0.05, the double-peak structure has essentially vanished in comparison to at x =0.16 due to the superposition of the strong fcc contribution. (iv) The 6-eV feature [19,31] above the main 2p 3/2 peak is prominent in Ni metal x =0.0) that is associated with electron correlation effects and narrow-band phenomena [32]. The intensity of the 6-eV feature is very low in the Ni 1−x C x films in comparison to Ni metal even at x =0.05 due to more delocalized bands.…”

“…Moreover, the 6-eV feature in the Ni XAS spectra that signifies electron correlation effects and narrow-band phenomena in metallic Ni [19,31] is washed out in the Ni 1−x C x samples due to the Ni 3d-C 2p orbital overlap that changes the properties of Ni already at very low carbon content. Thus, the spectral profiles of the Ni 1−x C x samples exhibit carbide signatures and exclude metallic nickel.…”

Spectroscopic study of Ni-rich Al–Co–Ni quasicrystal

“…In turn, the partial TM 3d DOS may be obtained from comparison of the on-or anti-resonance spectra with the offresonance one recorded at the excitation photon energy sufficiently far from the threshold. In the present study, we have subtracted the anti-resonance spectra from the off-resonance one, because (1) the huge resonant Auger signals overlap with the main TM 3d band at the on-resonance region and (2) the resonance enhancement of the Ni 3d main band is small due to the high initial 3d 10 configuration [14,20,25]. Thus obtained results are also shown as difference spectra in Figure 2.…”