Symmetry Analysis of the Fermi Surface States of Sr2RuO4by Display-Type Photoelectron Spectroscopy

Angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) data are usually measured spectrum by spectrum at various emission angles or photon energies in order to observe the dispersion of energy bands in solids and on their surfaces. In these lecture notes an alternative experimental procedure is described which yields a direct mapping of constant energy surfaces within the band structure, and specifically of the Fermi surface. This approach appears very promising, in particular when applied to magnetic systems and systems with narrow bands. Fermi surfaces of surface states are seen in direct relation to the underlying bulk Fermi surface.

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New insight on the role of localisation in the electronic structure of the Si(111)(7 × 7) surfaces

Scientific Reports ◽

10.1038/s41598-021-94664-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. E. Dávila ◽

J. Ávila ◽

I. R. Colambo ◽

D. B. Putungan ◽

D. P. Woodruff ◽

...

Keyword(s):

Fermi Surface ◽

Photoelectron Spectroscopy ◽

Surface States ◽

Emission Angle ◽

Final State ◽

Surface Mapping ◽

Arpes Data ◽

Reconstructed Surface ◽

Bulk Band

AbstractNew angle-resolved photoelectron spectroscopy (ARPES) data, recorded at several different photon energies from the Si(111)(7 × 7) surface, show that the well-known S1 and S2 surface states that lie in the bulk band gap are localised at specific (adatom and rest atom) sites on the reconstructed surface. The variations in the photoemission intensity from these states as a function of polar and azimuthal emission angle, and incident photon energy, are not consistent with Fermi surface mapping but are well-described by calculations of the multiple elastic scattering in the final state. This localisation of the most shallowly bound S1 state is consistent with the lack of significant dispersion, with no evidence of Fermi surface crossing, implying that the surface is not, as has been previously proposed, metallic in character. Our findings highlight the importance of final state scattering in interpreting ARPES data, an aspect that is routinely ignored and can lead to misleading conclusions.

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Electronic and Vibrational Properties of Single Crystal Surfaces of NiAl

MRS Proceedings ◽

10.1557/proc-83-47 ◽

1986 ◽

Vol 83 ◽

Author(s):

S.-C. Lui ◽

J. M. Mundenar ◽

E. W. Plummer ◽

M. E. Mostoller ◽

R. M. Nicklow ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Nearest Neighbor ◽

Surface States ◽

Active Surface ◽

Atomic Displacement ◽

Inelastic Electron ◽

Crystal Surfaces ◽

Single Crystal Surfaces ◽

Nial Alloy ◽

Bulk Surface

ABSTRACTSurface and bulk electronic structure of the ordered NiAl alloy were measured using angle resolved photoelectron spectroscopy. The measured bulk d-bands (Ni like) were observed to be narrower than theoretically calculated d band widths which are 20 to 40% wider (depending upon what is used as a measure of the width). At least two surface states were observed on both the (110) and (111) surfaces. The nature of these surface states and their relationship to the bulk band structure is discussed. Dispersion of bulk phonons was measured by neutron scattering and fitted with a fourth nearest neighbor Born-von Karman model. Dipole active surface phonons on the (110) and (111) surfaces were observed by inelastic electron scattering and the frequencies also calculated assuming a truncated bulk surface. The calculated surface modes present a qualitative picture of the atomic displacement at each surface and also show that the surface phonon energy and intensity depends upon the structure of the surface.

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Summary Abstract: Surface states at the (110) surface of InAs and InSb and the growth of AlAs at submonolayer coverage of Al studied by angle-resolved photoelectron spectroscopy

Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena ◽

10.1116/1.583515 ◽

1986 ◽

Vol 4 (4) ◽

pp. 900 ◽

Cited By ~ 11

Author(s):

H. W. Richter

Keyword(s):

Photoelectron Spectroscopy ◽

Surface States

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Mapping the fermi surface of graphite with a display-type photoelectron spectrometer

Applied Physics A Solids and Surface ◽

10.1007/bf00324768 ◽

1991 ◽

Vol 52 (5) ◽

pp. 299-301 ◽

Cited By ~ 71

Author(s):

A. Santoni ◽

L. J. Terminello ◽

F. J. Himpsel ◽

T Takahashi

Keyword(s):

Fermi Surface ◽

Display Type

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Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS2

Science Advances ◽

10.1126/sciadv.abd5000 ◽

2020 ◽

Vol 6 (51) ◽

pp. eabd5000

Author(s):

Niels B. M. Schröter ◽

Iñigo Robredo ◽

Sebastian Klemenz ◽

Robert J. Kirby ◽

Jonas A. Krieger ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Surface States ◽

Anomalous Hall Effect ◽

Half Metallicity ◽

Spintronic Devices ◽

Topological Materials ◽

Fermi Arcs ◽

Half Metal ◽

Minority Spin ◽

Electron Pocket

Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.

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TiO2/Dye/Electrolyte Interface Engineering by Atomic Layer Deposited Ultra Thin SiO2 for Improved Dye Sensitized Solar Cell Performance

MRS Proceedings ◽

10.1557/proc-1260-t10-37 ◽

2010 ◽

Vol 1260 ◽

Cited By ~ 1

Author(s):

Mariyappan Shanmugam ◽

Braden Bills ◽

Mahdi Farrokh Baroughi

Keyword(s):

Photoelectron Spectroscopy ◽

Short Circuit ◽

Photovoltaic Performance ◽

Dye Sensitized Solar Cells ◽

Surface States ◽

Atomic Layer ◽

Open Circuit ◽

Solar Cell Performance ◽

Dye Sensitized ◽

Layer Deposition

AbstractThe short circuit density (JSC) and open circuit voltage (VOC) of dye sensitized solar cells (DSSCs) were improved from 9.8 to 17.8 mA/cm2 and 728 to 743 mV by depositing an ultra thin SiO2 layer on mesoporous TiO2 using Atomic Layer Deposition (ALD) method. X ray photoelectron spectroscopy confirmed the growth of SiO2 on mesoporous TiO2 surface. It was also observed that the enhancement in DSSC performance highly depends on the thickness of the ALD grown SiO2 layers on mesoporous TiO2. Compared to the reference DSSC which used untreated TiO2, incorporation of 5 ALD cycles (about 5 atomic layers) of SiO2 on mesoporous TiO2 resulted in 80 % enhancement (E) in the photoconversion efficiency from 4 to 7.2%. It is believed that the deposition of the ultra thin SiO2 film on mesoporous TiO2 modifies the density and activity of the surface states and an optimized layer thickness (5 cycles) leads to significant improvement in the DSSC performance. The enhanced photovoltaic performance was confirmed by dark and illuminated I-V and external quantum efficiency (EQE) measurements.

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NEW ELECTRONIC STATES ON CLEAN Si(110)-“16×2” SURFACES

Surface Review and Letters ◽

10.1142/s0218625x95000546 ◽

1995 ◽

Vol 02 (05) ◽

pp. 573-577 ◽

Cited By ~ 5

Author(s):

A. CRICENTI ◽

B. NESTERENKO ◽

P. PERFETTI ◽

G. LE LAY ◽

C. SEBENNE

Keyword(s):

Electronic Properties ◽

Brillouin Zone ◽

Photoelectron Spectroscopy ◽

Structural Model ◽

Electronic States ◽

Surface States ◽

Ultraviolet Photoelectron Spectroscopy ◽

Surface Brillouin Zone ◽

Differential Reflectivity

The electronic properties of a clean Si (110)-“16×2” surface have been studied by angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) and surface differential reflectivity (SDR). Four surface states have been recognized by ARUPS and their dispersions have been mapped along the main symmetry lines in the surface Brillouin zone. SDR experiments revealed transitions between filled and empty surface states at ~ 1.8, 2.4, and 2.9 eV. The results are explained on the basis of a new structural model of the Si (110)-“16×2” phase.

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