Work function of a quasicrystal surface: Icosahedral Al–Pd–Mn

Ünal, Barış; Sato, Yu; McCarty, K. F.; Bartelt, N. C.; Duden, Thomas; Jenks, Cynthia J.; Schmid, Andreas K.; Thiel, Patricia A.

doi:10.1116/1.3168561

Cited by 18 publications

(10 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We measure work function changes using the criteria of the energy that gives 90% reflection. 55 In this manner, we -14 -find a small difference between the work functions of R30-and R0-covered Ir(111), with R30 being about ∼0.06 eV lower than R0. 56 Using literature values for the work function of clean Ir(111), Φ Ir = 5.7-5.76 eV, 57,58 we determine the work function of the LEEM electron source to Khomyakov et al 14 modeled the work function of many metals, but not Ir, covered by monolayer graphene.…”

Section: Work Functions Of R0 and R30 Graphenementioning

confidence: 59%

In-plane orientation effects on the electronic structure, stability, and Raman scattering of monolayer graphene on Ir(111)

Starodub

Bostwick²,

Moreschini³

et al. 2011

Phys. Rev. B

156

190

View full text Add to dashboard Cite

We employ angle-resolved photoemission spectroscopy (ARPES) to investigate the electronic structures of two rotational variants of epitaxial, single-layer graphene on Ir(111). As grown, the more-abundant R0 variant is nearly charge-neutral, with strong hybridization between graphene and Ir bands near the Fermi level. The graphene Fermi surface and its replicas exactly coincide with Van Hove singularities in the Ir Fermi surface. Sublattice symmetry breaking introduces a small gap-inducing potential at the Dirac crossing, which is revealed by n-doping the graphene using K atoms. The energy gaps between main and replica bands (originating from the moiré interference pattern between graphene and Ir lattices) is shown to be non-uniform along the minizone boundary due to hybridization with Ir bands. An electronically mediated interaction is proposed to account for the stability of the R0 variant. The variant rotated 30° in-plane, R30, is p-doped as grown and K doping reveals no band gap at the Dirac crossing. No replica bands are found in ARPES measurements. Raman spectra from the R30 variant exhibit the characteristic phonon modes of graphene, while R0 spectra are featureless. These results show that the film/substrate interaction changes from chemisorption (R0) to physisorption (R30) with in-plane orientation. Finally, graphene-covered Ir has a work function lower than the clean substrate but higher than graphite.-2 -

show abstract

Section: Work Functions Of R0 and R30 Graphenementioning

confidence: 59%

In-plane orientation effects on the electronic structure, stability, and Raman scattering of monolayer graphene on Ir(111)

Starodub

Bostwick²,

Moreschini³

et al. 2011

Phys. Rev. B

156

190

View full text Add to dashboard Cite

show abstract

“…Changes in the apparent mirror potential (changes in start voltage corresponding to mirror imaging conditions) in the LEEM images directly correspond to the shift in the effective surface potential, i.e., shift of the start voltage towards lower values indicates higher surface potential of the sample. In a number of the LEEM studies, such potential shift towards lower value is regarded as corresponding to lowering of the work function of the surface 40…”

Section: Resultsmentioning

confidence: 99%

Real‐Time Microscopy of Reorientation Driven Nucleation and Growth in Pentacene Thin Films on Silicon Dioxide

Abdullah

Fujikawa

Sakurai

et al. 2013

Adv Funct Materials

View full text Add to dashboard Cite

The role of molecular reorientation processes in the self‐assembly of anisotropic molecules, such as pentacene (Pn) is studied utilizing a unique capability of low‐energy electron microscopy (LEEM) for the real‐time investigation of the film growth. In Pn film on SiO2, a layer‐by‐layer growth is observed, albeit different from the expected Volmer–Weber growth mode typical for the systems with lower adhesion (weak interfacial interaction). The observed growth mechanism is also different than conventional concept of layer‐by‐layer, or Frank van der Merwe growth. In the Pn/SiO2 system the nucleation density decreases in each consecutive layer, at least up to four monolayers. This growth mechanism is hereafter named inverse Stranski‐Krastanov growth. Furthermore, in this growth system the second layer islands nucleate preferentially at the domain boundaries formed by the interconnections of the bottom (first layer) domains. The top layer overgrows bottom layer with its own, initial in‐plane crystal orientation, regardless of the in‐plane orientations in underlying Pn domains. The dark‐field LEEM imaging allows us to distinguish between Pn domains having different azimuthal direction of molecular tilt. LEEM intensity versus start voltage (LEEM I–V) curves taken in the vicinity of mirror potential from the first and second layer Pn islands show that the surface potential of the second layer is higher by about 0.05 eV than that of the first layer, while the surface potentials for the epitaxial and non‐epitaxial parts of the second layer island are identical.

show abstract

“…A slightly smaller value of the work function (4.75− 4.91 eV) was reported previously from low-energy electron microscopy. 34 Considering the uncertainty of measurement of the work function ranging from 4.75 to 5 eV, the position of feature B (0.85-1.1 eV below E vac for normal incidence) is close to the expected value (0.85 eV) for the n= 1 image potential state. While the width of an image potential state is very small (16 meV for n= 1), 35,36 the experimental energy resolution is much larger (0.5 eV).…”

Section: Resultsmentioning

confidence: 99%

Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

et al. 2014

View full text Add to dashboard Cite

We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15±0.1)me and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i-Al-Pd-Mn as predicted by density functional theory calculations and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i-Al-Pd-Mn with the free electron like image potential states. Our investigation of the energy region immediately above EF provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations.

show abstract

Work function of a quasicrystal surface: Icosahedral Al–Pd–Mn

Cited by 18 publications

References 19 publications

In-plane orientation effects on the electronic structure, stability, and Raman scattering of monolayer graphene on Ir(111)

In-plane orientation effects on the electronic structure, stability, and Raman scattering of monolayer graphene on Ir(111)

Real‐Time Microscopy of Reorientation Driven Nucleation and Growth in Pentacene Thin Films on Silicon Dioxide

Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

Contact Info

Product

Resources

About