Two‐Electron Spectroscopy Versus Single‐Electron Spectroscopy for Studying Secondary Emission from Surfaces

Samarin, Sergey; Artamonov, O.M.; Sergeant, Anthony; Williams, James

doi:10.1002/3527603425.ch6

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…We used two experimental set-ups, described elsewhere [16,17], for measuring the momentum distribution of correlated electron pairs. Our setup uses a spin-polarized incident beam and second has an extremely large acceptance angle that allows observation of the pair diffraction at a low primary electron energy [6].…”

Section: Methodsmentioning

confidence: 99%

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Emission of correlated electron pairs from Au(111) and Cu(111) surfaces under low-energy electron impact: Contribution of surface states, d-states and spin effects

Samarin

Artamonov

Guagliardo³

et al. 2015

Journal of Electron Spectroscopy and Related Phenomena

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The emission of correlated electron pairs excited from surfaces of Au(111) and Cu(111) by low-energy electrons is measured and analyzed. Energy and momentum conservation allows identification of electron pairs involving excitation of electrons from Shockley surface states and from valence d-states. The relative contributions of surface and d-states to the measured spectra of correlated electron pairs is shown to depend on the primary electron energy and is larger from surface states at relatively small primary energies. The use of a spin-polarized incident electron beam highlights the spin effects in producing an electron pair. Measurements show that spin effects are larger for the pair excitation from the valence d-states than for pairs excited from the surface states.

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Section: Methodsmentioning

confidence: 99%

“…Surface states on a Cu(111) surface were studied by the (e,2e) technique using different experimental set-ups [16,17]. We observed a pronounced maximum in the binding energy spectrum about 0.5 eV below the Fermi level(see Fig.…”

Section: Excitation Of Electron Pairs From a Cu Surfacementioning

confidence: 96%

Emission of correlated electron pairs from Au(111) and Cu(111) surfaces under low-energy electron impact: Contribution of surface states, d-states and spin effects

Samarin

Artamonov

Guagliardo³

et al. 2015

Journal of Electron Spectroscopy and Related Phenomena

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A First‐Principles Scheme for Calculating the Electronic Structure of Strongly Correlated Materials: GW+DMFT

Aryasetiawan¹,

Biermann

Georges

2004

Correlation Spectroscopy of Surfaces, Thin Films, and Nanostructures

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Strongly correlated systems are characterized by partially occupied localized orbitals such as found in transition metal oxides or 4f metals. Here the problem is often more of qualitative rather than quantitative nature. It is often found that the LDA predicts a transition metal oxide to be a metal whereas experimentally it is an antiferromagnetic insulator. To cite some examples, LaMnO 3 , famous for its colossal magnetoresistance, and La 2 CuO 4 , a well-known parent compound of high-temperature superconductors, are antiferromagnetic insulators but predicted to be metals by the LDA [39]. In cases where the LDA does predict the correct structure, it is legitimate to ask if the one-particle spectrum is also reproduced correctly. According to the currently accepted interpretation, transition metal oxides may be classified as charge-transfer insulators [18,42], which are characterized by the presence of occupied and unoccupied 3d bands with the oxygen 2p band in between. The gap is then formed by the oxygen 2p and unoccupied 3d bands, unlike the gap in LDA, which is formed by the 3d states (Mott-Hubbard gap). A more appropriate interpretation is to say that the highest valence state is a charge-transfer state: During photoemission a hole is created in the transition metal site but due to the strong 3d Coulomb repulsion it is energetically more favourable for the hole to hop to the oxygen site despite the cost in energy transfer. A number of experimental data, notably 2p core photoemission resonance, suggest that the charge-transfer picture is more appropriate to describe the electronic structure of transition metal oxides. And of course in the case of 4f metals, the LDA, being a one-particle theory, is totally incapable of yielding the incoherent part of the spectral function or satellite structures.The difficulties encountered by the LDA discussed above have prompted a number of attempts at improving the LDA. Notable among these is the GW approximation (GWA), developed systematically by Hedin in the early sixties [20]. He showed that the self-energy can be formally expanded in powers of the screened interaction W , the lowest term being iGW, where G is the Green function. Due to computational difficulties, for a long time the applications of the GWA were restricted to the electron gas. With the rapid progress in computer power, applications to realistic materials eventually became possible about two decades ago. Numerous applications to semiconductors and insulators reveal that in most cases the GWA [10,12] removes a large fraction of the LDA band-gap error. Applications to alkalis show band narrowing from the LDA values and account for more than half of the LDA error (although controversy about this issue still remains [29]).The success of the GWA in sp materials has prompted further applications to more strongly correlated systems. For this type of materials the GWA has been found to be less successful. For example, GW calculation on nickel [8] does reproduce the photoemission quasiparticle band structure rather...

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Anisotropy of spin-orbit interaction in W(110) by spin-polarized two-electron spectroscopy

et al. 2005

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Two‐Electron Spectroscopy Versus Single‐Electron Spectroscopy for Studying Secondary Emission from Surfaces

Cited by 3 publications

References 16 publications

Emission of correlated electron pairs from Au(111) and Cu(111) surfaces under low-energy electron impact: Contribution of surface states, d-states and spin effects

Emission of correlated electron pairs from Au(111) and Cu(111) surfaces under low-energy electron impact: Contribution of surface states, d-states and spin effects

A First‐Principles Scheme for Calculating the Electronic Structure of Strongly Correlated Materials: GW+DMFT

Anisotropy of spin-orbit interaction in W(110) by spin-polarized two-electron spectroscopy

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