Electronic and magnetic structure of the Cr(001) surface

Habibi, Parwana; Barreteau, Cyrille

doi:10.1088/0953-8984/25/14/146002

Cited by 15 publications

(22 citation statements)

References 23 publications

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“…1 the projected density of states of the 3d-states are plotted for a non spin-polarized and spin-polarized GGA calculation. These spectra are in very good agreement with what is reported in literature 10,12,16 . For example the results of Ref.…”

Section: A Ggasupporting

confidence: 93%

“…After this discovery many experimental and theoretical investigations were performed in order to understand the physical origin of this phenomenon. The first theoretical explanation was that of a single particle d z 2 surface state 9,10 . However, in order to predict the correct resonance position within this picture an unrealistic reduction of the magnetic polarization was required.…”

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confidence: 99%

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Origin of the quasiparticle peak in the spectral density of Cr(001) surfaces

et al. 2017

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In the spectral density of Cr(001) surfaces a sharp resonance close to the Fermi level is observed in both experiment and theory. For the physical origin of this peak two mechanisms were proposed. A single particle d z 2 surface state renormalised by electron-phonon coupling and an orbital Kondo effect due to the degenerate dxz/dyz states. Despite several experimental and theoretical investigations, the origin is still under debate. In this work we address this problem by two different approaches of the dynamical mean-field theory. First, by the spin-polarized T-matrix fluctuation exchange approximation suitable for weakly and moderately correlated systems. Second, by the non-crossing approximation derived in the limit of weak hybridization (i.e. for strongly correlated systems) capturing Kondo-like processes. By using recent continuous-time quantum Monte Carlo calculations as a benchmark, we find that the high-energy features, everything except the resonance, of the spectrum is captured within the spin-polarized T-matrix fluctuation exchange approximation. More precisely the particle-particle processes provide the main contribution. For the non-crossing approximation it appears that spin-polarized calculations suffer from spurious behavior at the Fermi level. Then, we turned to non spin-polarized calculations to avoid this unphysical behavior. By employing two plausible starting hybridization functions, it is observed that the characteristics of the resonance are crucially dependent on the starting point. It appears that only one of these starting hybridizations could result in an orbital Kondo resonance in the presence of a strong magnetic field like in the Cr(001) surface. It is for a future investigation to first resolve the unphysical behavior within the spin-polarized non-crossing approximation and then check for an orbital Kondo resonance.

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Section: A Ggasupporting

confidence: 93%

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confidence: 99%

Origin of the quasiparticle peak in the spectral density of Cr(001) surfaces

et al. 2017

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“…that has been associated to a s − p z − d z 2 surface state and an electronic state around 1 V, both displaying spin contrast on the conductance images [19,20]. Two spectra associated with a molecule lying on a spin-down terrace (upper images in the inset) and a molecule on a spin-up terrace (lower images in the inset) are shown, respectively, in blue and red.…”

Section: B Sp-sts Measurementsmentioning

confidence: 99%

Symmetry-selected spin-split hybrid states inC60/ferromagneticinterfaces

Barreteau

Kawahara

et al. 2016

Phys. Rev. B

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. (2016). Symmetryselected spin-split hybrid states in C-60/ferromagnetic interfaces. Physical Review B, 93(8) The understanding of orbital hybridization and spin polarization at the organic-ferromagnetic interface is essential in the search for efficient hybrid spintronic devices. Here, using first-principles calculations, we report a systematic study of spin-split hybrid states of C 60 deposited on various ferromagnetic surfaces: bcc-Cr(001), bccFe(001), bcc-Co(001), fcc-Co(001), and hcp-Co(0001). We show that the adsorption geometry of the molecule with respect to the surface crystallographic orientation of the magnetic substrate as well as the strength of the interaction play a crucial role in the spin polarization of the hybrid orbitals. We find that a large spin polarization in vacuum above the buckyball can only be achieved if the molecule is adsorbed upon a bcc-(001) surface by its pentagonal ring. Therefore, bcc-Cr(001), bcc-Fe(001), and bcc-Co(001) are the optimal candidates. Spin-polarized scanning tunneling spectroscopy measurements on single C 60 adsorbed on Cr(001) and Co/Pt(111) also confirm that the symmetry both of the substrate and of the molecular conformation has a strong influence on the induced spin polarization. Our finding may give valuable insights for further engineering of spin filtering devices through single molecular orbitals.

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“…The first idea was to explain the resonance in terms of a single particle d z 2 surface state. 7,9 A shortcoming of this idea was the unrealistic reduction of the magnetic moment required to obtain the correct resonance position. Another interpretation in terms of an orbital Kondo effect involving the degenerate d xz and d yz states was proposed to explain the scanning tunneling spectroscopy experiments on very clean Cr(001)-surfaces.…”

Section: Introductionmentioning

confidence: 99%

Ab initio study of the electron-phonon coupling at the Cr(001) surface

2018

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It is experimentally well established that the Cr(001)-surface exhibits a sharp resonance around the Fermi level. However, there is no consensus about its physical origin. It is proposed to be either due to a single particle d z 2 surface state renormalised by electron-phonon coupling or the orbital Kondo effect involving the degenerate dxz/dyz states. In this work we examine the electron-phonon coupling of the Cr(001)-surface by means of ab-initio calculations in the form of density functional perturbation theory. More precisely, the electron-phonon mass-enhancement factor of the surface layer is investigated for the 3d states. For the majority and minority spin d z 2 surface states we find values of 0.19 and 0.16. We show that these calculated electron-phonon mass-enhancement factors are not in agreement with the experimental data even if we use realistic values for the temperature range and surface Debye frequency for the fit of the experimental data. More precisely, then experimentally an electron-phonon mass-enhancement factor of 0.70 ± 0.10 is obtained, which is not in agreement with our calculated values of 0.19 and 0.16. Therefore, we conclude that the experimentally observed resonance at the Cr(001)-surface is not due to polaronic effects, but due to electron-electron correlation effects.

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Electronic and magnetic structure of the Cr(001) surface

Cited by 15 publications

References 23 publications

Origin of the quasiparticle peak in the spectral density of Cr(001) surfaces

Origin of the quasiparticle peak in the spectral density of Cr(001) surfaces

Symmetry-selected spin-split hybrid states inC60/ferromagneticinterfaces

Ab initio study of the electron-phonon coupling at the Cr(001) surface

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