Photoemission Spectroscopy with Very High Energy Resolution: Studying the Influence of Electronic Correlations on the Millielectronvolt Scale

Reinert, Friedrich; Hüfner, S.

doi:10.1007/3-540-68133-7_2

Cited by 5 publications

(8 citation statements)

References 107 publications

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“…To understand the origin of the hump, we performed a fitting to using multiple Eliashberg spectral functions [green dashed curves in Fig. 2(d)] following the Debye model [33]. The fitting resulted in two Debye frequencies 75 ± 6 and 195 ± 10 meV, which are very much in agreement with the energy positions of the kinks found from the band dispersion [Fig.…”

Section: E-e F (Ev)supporting

confidence: 56%

Anomalous band renormalization due to a high-energy kink in K0.65RhO2 with colossal thermoelectric power factor

Changdar

Shipunov

Joseph

et al. 2021

Phys. Rev. Materials

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We identify highly correlated hole pocket on the Fermi surface of colossal thermoelectric material K 0.65 RhO 2 , studied using high-resolution angle-resolved photoemission spectroscopy (ARPES) and density-functional theory (DFT) calculations. Most importantly, two kinks at binding energies of 75 and 195 meV have been observed below the Fermi level. While the low-energy kink at 75 meV can be understood as a result of the electron-phonon interaction, the high-energy kink at 195 meV is a discovery of this system, leading to anomalous band renormalization, possibly originated from the bosonic excitations at higher frequencies. We further notice that the high-energy anomaly has important implications on the colossal thermoelectric power of K 0.65 RhO 2 .

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Section: E-e F (Ev)supporting

confidence: 56%

Anomalous band renormalization due to a high-energy kink in K0.65RhO2 with colossal thermoelectric power factor

Changdar

Shipunov

Joseph

et al. 2021

Phys. Rev. Materials

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“…This value contains the energy resolution and contributions from extrinsic broadening effects as discussed in [22]. Such a linear temperature dependence is known from the high-temperature limit of the Debye model, where the slope is immediately related to the electron-phonon coupling parameter λ by ∂Γ/∂T = 2πλk B [39]. From a linear least-squares fit of the temperature dependence we obtain here λ ≈ 0.7, which would indicate a very strong electron-phonon coupling.…”

mentioning

confidence: 61%

“…2 shows the result of a quantitative line width analysis. The individual values for the full width at half maximum (FWHM) were obtained by a two step analysis: To restore the photoemission signal above E F , the spectra have been normalized to the Fermi-Dirac distribution (FDD) [21,[37][38][39][40] first, and then fitted by a Lorentzian, which describes the line shape of the peak reasonably well (see inset of Fig. 2).…”

mentioning

confidence: 99%

Low-energy scale excitations in the spectral function of organic monolayer systems

et al. 2012

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Using high-resolution photoemission spectroscopy we demonstrate that the electronic structure of several organic monolayer systems, in particular 1,4,5,8-naphthalene tetracarboxylic dianhydride and Copper-phtalocyanine on Ag(111), is characterized by a peculiar excitation feature right at the Fermi level. This feature displays a strong temperature dependence and is immediatly connected to the binding energy of the molecular states, determined by the coupling between the molecule and the substrate. At low temperatures, the line-width of this feature, appearing on top of the partly occupied lowest unoccupied molecular orbital of the free molecule, amounts to only ≈ 25 meV, representing an unusually small energy scale for electronic excitations in these systems. We discuss possible origins, related e.g. to many-body excitations in the organic-metal adsorbate system, in particular a generalized Kondo scenario based on the single impurity Anderson model. For more than twenty years there has been a thorough investigation on π-conjugated organic molecules, which have shown to be suitable for the application in organic electronic devices [1][2][3]. These molecules often form long-range ordered films on single-crystalline metal substrates, allowing a systematic and fundamental study by various surface sensitive techniques. In particular from electron spectroscopy methods, as photoemission spectroscopy (PES), inverse photoemission (IPES), and x-ray absorption (XAS), deep insight into many important features of the electronic properties of condensed films and their interfaces has been achieved [4][5][6][7][8]. The latter are of particular importance since they crucially determine the properties of possible devices. Additional microscopic and spectroscopic information has been obtained by use of scanning tunneling microscopy (STM), leading to complementary information about the relation between geometrical and electronic structure [9][10][11][12].Usually, even the spectra of highly ordered films show features with a line-width of several hundreds of meV, mostly determined by vibronic excitations within the adsorbed molecule [7,13,14]. Therefore, even experiments with modern high-resolution photoemission spectrometers for VUV photoemission (UPS) display only features which are about two orders of magnitude larger than the most narrow peaks in other solid state or surface systems [15]. Local spectroscopic measurements by STM, on the other hand, show narrow features in the tunneling conductivity measurements through a single molecule [10,[16][17][18][19], which have been attributed to a possible Kondo like process within the charge transport through * present address: SOLEIL L'Orme des Merisiers, Saint-Aubin -BP 48, 91192 GIF-sur-YVETTE CEDEX FRANCE SOLEIL, Paris, France the adsorbed molecule. However, neither a direct evidence of a local magnetic moment, necessary for the Kondo effect, nor an immediate experimental observation of the spectral function does exist yet.Here we report about a high-resolution photoemission study o...

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“…21 One feature is the explicit derivation in the atomic orbital and atomic displacement basis. In principle, it is possible to write the vibrational modes in terms of two bases.…”

Section: Electron-vibration Self-energymentioning

confidence: 99%

“…This is a rather standard way to approximate the electron-vibration coupling in photoemission spectroscopy at low temperatures. 21 To demonstrate, how Eq. ͑A22͒ is used, we show the generic result for Einstein model for vibrational density of states, g IJ ͑⍀͒ = ␦͑⍀ − ⍀ q ͒, and a constant electronic density of states, ␦␥ ͑E͒ = .…”

Section: + ប⍀͖͒D⍀ ͑A20͒mentioning

confidence: 99%

Carrier wave effect in nonresonant inelastic scanning tunneling spectroscopy of molecules with delocalized frontier orbitals

2010

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In this work we present a method for simulating the electron-vibration coupling in adsorbate molecules using a tight-binding formalism for the electronic degrees of freedom and a real-space description of the molecular vibrations. First, we derive a formalism which is very transparent in recognizing the effect of a local vibrational perturbation on the local electronic structure at any location. Second, we apply the method to nonresonant inelastic electron-tunneling spectroscopy ͑IETS͒ of two sample molecules on generic model substrates as typically accessible within a scanning tunneling microscopy ͑STM͒ experiment. The foremost observation is that the intensity of the STM-IETS signal is not necessarily strongest in the spatial vicinity of the vibrational perturbation. Instead, it is dependent on the delocalization of the molecular orbitals, which may lead to a strong intensity quite far from the vibration. Since this is an effect of the electronic structure and not related to the transfer of the vibrational motion itself, the molecular orbitals can be treated as "carrier waves" of the signal from a vibrational perturbation. This effect may be important in determining the orientation of an adsorbed molecule on a substrate surface or in manipulating adsorbed molecules with an STM tip.

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Photoemission Spectroscopy with Very High Energy Resolution: Studying the Influence of Electronic Correlations on the Millielectronvolt Scale

Cited by 5 publications

References 107 publications

Anomalous band renormalization due to a high-energy kink in K0.65RhO2 with colossal thermoelectric power factor

Anomalous band renormalization due to a high-energy kink in K0.65RhO2 with colossal thermoelectric power factor

Low-energy scale excitations in the spectral function of organic monolayer systems

Carrier wave effect in nonresonant inelastic scanning tunneling spectroscopy of molecules with delocalized frontier orbitals

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