Photoemission study of CoO

Correlated band structure of NiO, CoO, and MnO by variational cluster approximation

“…This part of the electronic structure is not at all reproduced by band struture calculations which on the contray would predict the d n → d n−1 transitions near the valence band top. And finally experimental band structures measured by angle resolved photoelectron spectroscopy (ARPES) show that for all compounds, NiO, CoO and MnO, the TM-derived bands near the valence band top are almost dispersionless [5,8,10]. This is also in contradition to LDA calculations which predicts band widths of around 2eV for the TM3d-derived bands.…”

“…Figure 11 compares the angle integrated spectra at different photon energies and the kintegrated spectral function obatined by the VCA, Figure 12 shows the dispersion along Γ → X and ARPES data from Shen et al [5] and Brookes et al [48]. The XPS spectrum for CoO starts out with a prominent peak at −3eV [5] and by Brookes et al [48] in CoO. Bottom: k-dependent spectral function for momenta along Γ − X for CoO.…”

“…From a comparison of X-ray photoemission spectroscopy (XPS) and bremsstrahlung isochromat spectroscopy (BIS) it was found [3] that the band gap predicted by LDA for antiferromagnetic is too small by a factor of ≈ 10. Moreover electron spectroscopy shows that the electronic structure remains essentially unchanged at the Néel temperature for both NiO [4] and CoO [5]. In both compounds there is practically no difference between the electronic spectra in the antiferromagnetic and paramagnetic phase.…”

“…Failure to predict the insulating ground state and the magnitude of the insulating gap is not the only shortcoming of LDA. In valence band photoemission spectroscopy (PES) all three oxides NiO, CoO and MnO show a 'satellite' at an energy of ≈ 6 − 8eV below the valence band top [5,7,8]. The Fano-like intensity variation with photon energy at the TM 3p → 3d threshold identifies this feature as being due to d n → d n−1 transitions [9].…”

Novel mesoscale defect structure on NiO(100) surfaces by atomic force microscopy

“…Its bulk antiferromagnetic nature lends itself to use in coupled layer magnetic storage media [38], [39] and [40] and the magnetic behavior of NiO nanoparticles is suitable for spin valves important in the rapidly developing fi eld of spintronics [41], [42], [43] and [44]. NiO surface properties have been well investigated [19], [45], [46], [47], [48], [49], [50], [51], [52], [53] and [54] and the band structure [55], [56], [57], [58], [59], [60] and [61] and crystallography of the ideal surface [62] and [63] are well-known. The NiO(1 0 0) cleavage plane [45], [62], [63] and [64] can produce, to within reasonable tolerances, well-ordered, stoichiometric substrates although cleaved surfaces have been reported to contain randomly-spaced step defects, approximately 25-100 nm apart, with the step heights in multiples of 2.1 Å, the Ni-O nearest-neighbor distance [52] and [54].…”