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

1986 ◽  
Vol 4 (4) ◽  
pp. 900 ◽  
Author(s):  
H. W. Richter
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface States

Electronic and Vibrational Properties of Single Crystal Surfaces of NiAl

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.

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

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.

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

2010 ◽  
Vol 1260 ◽  
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.

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

1995 ◽  
Vol 02 (05) ◽  
pp. 573-577 ◽  
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.

Angle-resolved photoelectron spectroscopy investigation of intrinsic surface states on the Ge(001)-(2 × 1) reconstructed surface

1983 ◽  
Vol 27 (6) ◽  
pp. 3924-3926 ◽  
Author(s):  
Jeffrey G. Nelson ◽  
William J. Gignac ◽  
R. Stanley Williams ◽  
Steven W. Robey ◽  
J. G. Tobin ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Reconstructed Surface

scholarly journals Фотоэмиссионные исследования электронной структуры GaN, выращенного методом молекулярно-пучковой эпитаксии с плазменной активацией азота

2019 ◽  
Vol 61 (12) ◽  
pp. 2294
Author(s):  
С.Н. Тимошнев ◽  
А.М. Мизеров ◽  
Г.В. Бенеманская ◽  
С.А. Кукушкин ◽  
А.Д. Буравлев
Keyword(s):  
Electronic Structure ◽  
Charge Transfer ◽  
Synchrotron Radiation ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
Experimental Studies ◽  
Surface States ◽  
Li Adsorption ◽  
Semiconductor Character

The results of experimental studies of the electronic and photoemission properties of an epitaxial GaN layer grown on a SiC/Si(111) substrate by plasma assisted molecular beam epitaxy are presented. The electronic structure of the GaN surface and ultrathin Li/GaN interface was first studied in situ under ultrahigh vacuum conditions under different Li coverages. The experiments were performed using photoelectron spectroscopy with synchrotron radiation in the photon energy range of 75–850 eV. The photoemission spectra in the region of the valence band and surface states and the photoemission spectra from the N 1s, Ga 3d, Li 2s core levels were studied for different submonolayer Li coverages. It is established that Li adsorption causes significant changes in the general form of the spectra induced by charge transfer between the Li layer and the lower N and Ga layers. It is established that the GaN surface has predominantly N-polarity. The semiconductor character of the Li / GaN interface is shown.

scholarly journals Spin-polarized Weyl cones and giant anomalous Nernst effect in ferromagnetic Heusler films

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Kazuki Sumida ◽  
Yuya Sakuraba ◽  
Keisuke Masuda ◽  
Takashi Kono ◽  
Masaaki Kakoki ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Remanent Magnetization ◽  
Room Temperature ◽  
High Efficiency ◽  
Quantum Critical Point ◽  
Surface States ◽  
Flat Band ◽  
Zero Field ◽  
Topological Quantum ◽  
Spin Polarized

AbstractWeyl semimetals are characterized by the presence of massless band dispersion in momentum space. When a Weyl semimetal meets magnetism, large anomalous transport properties emerge as a consequence of its topological nature. Here, using in−situ spin- and angle-resolved photoelectron spectroscopy combined with ab initio calculations, we visualize the spin-polarized Weyl cone and flat-band surface states of ferromagnetic Co2MnGa films with full remanent magnetization. We demonstrate that the anomalous Hall and Nernst conductivities systematically grow when the magnetization-induced massive Weyl cone at a Lifshitz quantum critical point approaches the Fermi energy, until a high anomalous Nernst thermopower of  ~6.2 μVK−1 is realized at room temperature. Given this topological quantum state and full remanent magnetization, Co2MnGa films are promising for realizing high efficiency heat flux and magnetic field sensing devices operable at room temperature and zero-field.

scholarly journals Surface-state Coulomb repulsion accelerates a metal-insulator transition in topological semimetal nanofilms

2020 ◽  
Vol 6 (12) ◽  
pp. eaaz5015 ◽  
Author(s):  
S. Ito ◽  
M. Arita ◽  
J. Haruyama ◽  
B. Feng ◽  
W.-C. Chen ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Surface States ◽  
Coulomb Repulsion ◽  
Metallic Surface ◽  
Nanoscale Transport ◽  
Flexible Control ◽  
Quantum Size ◽  
Insulating Phase

The emergence of quantization at the nanoscale, the quantum size effect (QSE), allows flexible control of matter and is a rich source of advanced functionalities. A QSE-induced transition into an insulating phase in semimetallic nanofilms was predicted for bismuth a half-century ago and has regained new interest with regard to its surface states exhibiting nontrivial electronic topology. Here, we reveal an unexpected mechanism of the transition by high-resolution angle-resolved photoelectron spectroscopy combined with theoretical calculations. Anomalous evolution and degeneracy of quantized energy levels indicate that increased Coulomb repulsion from the surface states deforms a quantum confinement potential with decreasing thickness. The potential deformation strongly modulates spatial distributions of quantized wave functions, which leads to acceleration of the transition beyond the original QSE picture. This discovery establishes a complete picture of the long-discussed transition and highlights a new class of size effects dominating nanoscale transport in systems with metallic surface states.

scholarly journals Effect of Annealing, Stoichiometry, and Surface on Magnetism of (Pr,Dy)FeCoB Microparticles Ensemble

2017 ◽  
Vol 62 (3) ◽  
pp. 1923-1930 ◽  
Author(s):  
E.N. Kablov ◽  
O.G. Ospennikova ◽  
E.I. Kunitsyna ◽  
V.P. Piskorskii ◽  
D.V. Korolev ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Phase Composition ◽  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Anisotropy Field ◽  
X Ray ◽  
Average Size ◽  
Thermal Stability Of ◽  
Effect Of Surface

AbstractMagnetic properties of powder (Pr,Dy)FeCoB ferrimagnetic alloys and effects of annealing, surface states were analyzed. X-ray photoelectron spectroscopy and Mössbauer spectra of powders indicate the effect of surface states on phase composition and magnetic properties of the studied powder, if particles average size is smaller than 10 μm. Effect of stoichiometry on magnetic anisotropy was found. Thermal stability of anisotropy field was proved by replacement of Fe atoms with Co atoms.

scholarly journals Электронная структура наноинтерфейса Cs/n-GaN(0001)

2018 ◽  
Vol 44 (6) ◽  
pp. 50
Author(s):  
Г.В. Бенеманская ◽  
М.Н. Лапушкин ◽  
Д.Е. Марченко ◽  
С.Н. Тимошнев
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Valence Band Maximum ◽  
Surface Electron ◽  
Electron States ◽  
Band Maximum ◽  
Metallic Character ◽  
First Time

AbstractElectronic structures of the n -GaN(0001) surface and Cs/ n -GaN(0001) interface with submonolayer Cs coverages were studied for the first time in situ by the photoelectron spectroscopy (PES) method. The spectra of photoemission from the valence band, surface electron states, and core levels (Ga 3 d , Cs 4 d , Cs 5 p ) under synchrotron excitation were measured in a range of photon energies within 50–150 eV. Evolution of the spectrum of surface states near the valence-band maximum was revealed by PES during the adsorption of Cs atoms. A metallic character of the Cs/ n -GaN(0001) nano-interface is demonstrated.

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