Electronic structure and growth of K, Rb, and Cs monolayers on graphite studied by photoemission

Algdal, Jonathan; Breitholtz, M.; Kihlgren, T.; Lindgren, S.Å.; Walldén, L.

doi:10.1103/physrevb.73.165409

Cited by 15 publications

(16 citation statements)

References 34 publications

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“…Comparing with reported ARPES experiments [21], it might be that the plasmaron excitations are responsible for the observed high-binding-energy shoulder. A future challenge is to perform a comparative study of the two types of plasmarons to find out (i) which one dominates and (ii) the key parameters for the h plasmarons and the e plasmarons, respectively.…”

Section: Discussionsupporting

confidence: 59%

“…The results indicate that losses due to the interaction of the escaping photoelectron and surface localized plasmons could give rise to satellites in the ARPES spectrum. The ARPES data of Algdal et al [21] for the system p(2 × 2)-K/graphite show an asymmetry of the quantum-well peak near normal emission which is consistent with additional losses below the peak.…”

Section: Introductionmentioning

confidence: 59%

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Plasmaron excitations in p(2×2)-K/graphite

2014

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Plasmarons formed by the compound of photoelectrons and acoustic surface-plasmon excitations is investigated in the system p(2 × 2)-K/graphite. The physics behind this type of plasmarons (e plasmarons) differs from the physics of plasmarons recently found in graphene, where the loss feature is argued to result from the photohole-plasmon interaction (h plasmarons). Based on first principles methods we calculate the dispersion of the e-plasmaron excitation rate, which yields a broad feature below the parabolic quantum-well band with a peak about 0.4 eV below the quantum-well band at the¯ point.

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Section: Discussionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 59%

Plasmaron excitations in p(2×2)-K/graphite

2014

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“…42 For K and Rb the high coverage phase consists of monolayer thick islands with close-packed atoms in 2 ϫ 2 order. 13,43 The effect of increasing the adatom coverage is just a larger island area but no significant compression of the atoms. This is reflected by coverage independent binding energies for core and valence states for the high coverage phase.…”

Section: Nonmetal-metal Transitionmentioning

confidence: 99%

“…Graphite is an alternative but when an alkali metal is adsorbed, a low temperature is needed to avoid intercalation or, for Na, three-dimensional ͑3D͒ growth. [12][13][14] A motivation for finding systems that realize near ideal metal quantum wells is that these provide unique opportunities to study many aspects of solid-state properties as witnessed by the wide range of experiments performed on the metal quantum well systems already uncovered. [15][16][17][18][19][20][21][22] In the present work the emphasis is on the characterization of Na/ Be͑0001͒ and K/Be͑0001͒ in the monolayer range but some measurements made at higher coverage indicate that both systems are benign in the sense that additional layers can be grown with atomic layer defined thickness.…”

Section: Introductionmentioning

confidence: 99%

Sodium and potassium monolayers on Be(0001) investigated by photoemission and electronic structure calculations

et al. 2008

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Photoemission spectra show that Be͑0001͒ surface states shift to lower energy with increasing Na or K coverage in the monolayer range. At an intermediate monolayer coverage a quantum well state appears near the Fermi edge and shifts to lower energy reaching saturation energy at full monolayer coverage. At full monolayer coverage low energy electron diffraction shows 2 ϫ 2 order for K while Na forms an incommensurate closepacked structure aligned with the substrate. As a result of the different structures, the photoemission spectra show qualitative differences that are explained by diffraction. First-principles calculations for Be͑0001͒ and p͑2 ϫ 2͒K / Be͑0001͒ reproduce reasonably the measured energy shifts and dispersions. Spectra recorded for the shallow alkali-metal core levels show that the adlayer is inhomogeneous in an intermediate coverage range. While this is not noted when the valence state energies are measured a linewidth change observed for one of the surface states is ascribed to this inhomogeneity. It is suggested that the onset of inhomogeneity is associated with the occupation of states in the quantum well band. Occupation of these states, which are highly localized to the adlayer, gives metal character to the layer over an increasing area as the coverage is increased making the film homogeneous at high monolayer coverage. An anomalous emission line is observed for both Na and K as a low energy companion to the quantum well state line becoming increasingly separated from this as the coverage increases. We suggest that the satellite is due to an energy loss associated with collective oscillations in the overlayer.

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“…Alkali metal-graphene system is also a topic 2 of great interest in device application and in the structural phase transition when alkali metal growth on graphene. Such a system has been a subject of intensive experimental and theoretical interest over the past twenty years [10][11][12][13][14][15][16]. Nevertheless, the nature of alkali metal interactions on graphite or graphene is still under much debate.…”

Section: Introductionmentioning

confidence: 99%

Charge oscillations and interaction between potassium adatoms on graphene studied by first-principles calculations

et al. 2015

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Interaction between K adatoms on graphene is investigated by first-principles calculations based on density function theory and analytical analyses based on the k• p perturbation theory. The calculation shows that there is a strong repulsion between K adatoms. The main origin of this strong repulsion is not from the dipole-dipole interaction as suggested for K adatom on graphite surface, but comes from the screened Coulomb interaction. Potassium adatom on graphene donates its s electron and becomes K + . The positively charged K adatom induces electron density oscillation on graphene which is responsible for the screened Coulomb repulsion between the K adatoms.PACS numbers: 68.65. Pq, 68.43.Fg, 71.15.Mb, 68.55.Ln § xiaojie@csrc.ac.cn * wangcz@ameslab.gov # kchang@semi.ac.cn 1 Coulomb impurity in graphene is a problem of fundamental interest due to the unique electronic structure of graphene. Because graphene has linear energy dispersion and very small density-of-states around the Fermi level and consists of two sub-lattices, the electronic structure and transport properties of graphene are very sensitive to impurities [1][2][3][4][5][6][7][8]. Understanding and manipulating the interaction among the Coulomb impurities and between the impurity atoms and carbon atoms on graphene provide an effective approach for engineering the electronic structures to meet various requirements in the application of graphene.While it is well-known that Coulomb or magnetic impurities on metal surface induce interesting phenomena such as Friedel oscillation in electron density thus the indirect interaction between the impurities, interaction between such impurities on graphene has not been well understood. It has been proposed that oscillation of the charge density induced by a charged impurity on graphene has a faster (δρ ~ r -3 ) decay than that in conventional 2D electron systems which decay as r -2 [5,7]. Calculations based on tight-binding models suggested that in addition to the long wavelength Friedel oscillation, a short wavelength modulation of electron density also emerges due to the two sub-lattices on graphene [4,9]. Energy-resolved maps of the local density-of-states by using STM also reveal electron density modulations on two different length scales, reflecting both intravalley and intervalley scattering [8].Despite of intensive studies, our understanding of the behavior of charge oscillation and especially impurity interactions on graphene is still far from being completed.Most of the previous theoretical studies are based on model Hamiltonians, a fully self-consistent first-principles calculation is highly desirable and can provide useful insight for a better understanding of the mechanism of impurities on graphene.In this paper, we performed first-principles calculations and analytical analyses based on the k•p perturbation theory to study the interaction between K adatoms on graphene and characterize the electron density oscillation behavior induced by the K adatoms. Potassium on graphene is chosen because ...

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Electronic structure and growth of K, Rb, and Cs monolayers on graphite studied by photoemission

Cited by 15 publications

References 34 publications

Plasmaron excitations in p(2×2)-K/graphite

Plasmaron excitations in p(2×2)-K/graphite

Sodium and potassium monolayers on Be(0001) investigated by photoemission and electronic structure calculations

Charge oscillations and interaction between potassium adatoms on graphene studied by first-principles calculations

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