Unoccupied electronic structure of graphite probed by angle-resolved photoemission spectroscopy

Mahatha, S. K.; Menon, Krishnakumar S. R.; Balasubramanian, T.

doi:10.1103/physrevb.84.113106

Cited by 10 publications

(6 citation statements)

References 19 publications

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“…This signifies that the observed anomalies involve hBN-dependent transitions that are inelastic in energy and/or momentum. Based on similar observations in few-layer graphene, we infer that they are signatures of secondary electrons ejected from the limited number of unoccupied final states available. − Alternatively, these could be from Umklapp-scattered electrons ejected from the underlying graphene, interacting with the hBN as they pass through the flaked material on their way out into vacuum …”

mentioning

confidence: 79%

Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride

et al. 2023

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Understanding the collective behavior of the quasiparticles in solid-state systems underpins the field of nonvolatile electronics, including the opportunity to control many-body effects for well-desired physical phenomena and their applications. Hexagonal boron nitride (hBN) is a wide-energy-bandgap semiconductor, showing immense potential as a platform for lowdimensional device heterostructures. It is an inert dielectric used for gated devices, having a negligible orbital hybridization when placed in contact with other systems. Despite its inertness, we discover a large electron mass enhancement in few-layer hBN affecting the lifetime of the π-band states. We show that the renormalization is phononmediated and consistent with both single-and multiple-phonon scattering events. Our findings thus unveil a so-far unknown manybody state in a wide-bandgap insulator, having important implications for devices using hBN as one of their building blocks.

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mentioning

confidence: 79%

Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride

et al. 2023

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“…For example, some samples cannot always be modeled well using DFT calculations. This could potentially be avoided by using a Wertheim–Walker profile with experimentally measured occupied and unoccupied states using experimental techniques, such as scanning tunneling spectroscopy or angular-resolved photoelectron spectroscopy, but this possibility has not been tested. Overall, in cases where a reliable DOS can be obtained for a postulated structure, our method allows a rigorous test of this structure based on the shape of the XPS line profile.…”

Section: Discussionmentioning

confidence: 99%

Predicting X-ray Photoelectron Peak Shapes: the Effect of Electronic Structure

et al. 2021

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X-ray photoelectron spectroscopy (XPS) is a widely used tool for quantitative analysis of surfaces, providing critical information about elemental composition and the chemical state(s) of each element. Quantitative analysis of XPS data requires fitting of curves corresponding to different chemical states with appropriate spectral lines. Traditionally, analysis of peak profiles is performed using peak shapes that have been determined empirically; however, these methods cannot readily account for changes in the symmetry of peak shapes due to differences in electronic structure. A physically rigorous technique is introduced herein that can fit symmetric and asymmetric peak profiles by determining the Wertheim− Walker profile based on densities of states calculated by density functional theory (DFT + WW). The DFT + WW method uniquely can accurately predict changes in XPS line shape due to changes in d-band filling, lattice contraction and expansion, and atomically precise chemical environments. A DFT + WW profile is suitable for applications where a hypothesized model structure of a material can be accurately calculated and, in these cases, the XPS fits provide a test of whether the hypothesized structure has a similar density of states to the experimental sample. This could allow improved peak assignment and improved interpretation of XP spectra. When applied to spectra from single-crystal transition-metal samples, the DFT + WW method gives excellent fits, with a similar accuracy to common peak profilesVoigt, Doniach−S ̌unjic, and Mahan. Furthermore, the DFT + WW method captures experimentally observed changes in the peak shape between bulk metals and overlayer structures. Overall, the DFT + WW method provides a clear link between electronic structure and XPS line profile, allowing for possible improvements in the interpretation of XP spectra.

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“…Figure 1d shows the ARPES spectra of in-situ cleaved graphite surface with known valence bands [27,28] along the M direction. ARPES spectra collected after growing 6 ML of Cu on graphite surface at RT are shown in figure 1e, where only weak intensity below 2 eV binding energy could be observed.…”

Section: Cu On Graphitementioning

confidence: 99%

Growth and photoemission spectroscopic studies of ultrathin noble metal films on graphite

Mahatha

Menon

2015

Pramana - J Phys

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Growth of Cu, Ag and Au thin films on graphite(0 0 0 1)surface and possible formation of quantum well (QW) states originating due to the confinement of thin film sp electrons within the band gap of graphite along M symmetry direction are investigated using low-energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES). Higher surface diffusivity and surface energy of Cu on graphite surface led to cluster growth and does not reveal any quantum size effect, while Ag and Au films grow epitaxially in spite of large lattice mismatch. However, better surface ordering has been achieved by growing Ag and Au at low temperature (LT), followed by room-temperature (RT) annealing which are evident from LEED and the presence of sharp Shockley-type surface state (SS) at Fermi level (E F ). ARPES study of Ag films on graphite does not show any QW states, whereas Au films demonstrate a very sharp SS, Au bulk bands and well-resolved QW states or resonances. The observed low in-plane dispersions of these Au QW states or resonances are compared with the dispersions obtained in the previous Au QW state studies as well as for free-standing Au films.

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Unoccupied electronic structure of graphite probed by angle-resolved photoemission spectroscopy

Cited by 10 publications

References 19 publications

Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride

Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride

Predicting X-ray Photoelectron Peak Shapes: the Effect of Electronic Structure

Growth and photoemission spectroscopic studies of ultrathin noble metal films on graphite

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