D. Marchenko

D. Marchenko
Helmholtz-Zentrum Berlin für Materialien und Energie | HZB · EM-AMGS

Dr. rer. nat.

About

100
Publications
18,697
Reads
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5,524
Citations
Additional affiliations
October 2015 - present
February 2013 - October 2015
Freie Universität Berlin
Position
  • PostDoc Position
January 2009 - January 2010
Helmholtz-Zentrum Berlin für Materialien und Energie
Position
  • Beamline Scientist / User Support

Publications

Publications (100)
Article
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It has recently been demonstrated that pentacene can serve as protection layer for graphene on SiC preserving the unique E(k) band dispersion after exposure to atmosphere and subsequent annealing in vacuum. We confirm the stability of the ideal graphene band dispersion but without any protection layer. We demonstrate this by angle-resolved photoemi...
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We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to "Mexican hat"-like through the formation of a flattened band. The mechanism is well applicable for bilayer graph...
Article
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Two-dimensional (2D) Dirac materials are electronically and structurally very sensitive to proximity effects. We demonstrate, however, the opposite effect: that the deposition of a monolayer 2D material could exercise a substantial influence on the substrate electronic structure. Here we investigate TiC(111) and show that a graphene overlayer produ...
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Graphene in spintronics is predominantly considered for spin current leads of high performance due to weak intrinsic spin-orbit coupling of the graphene p electrons. Externally induced large spin-orbit coupling opens the possibility of using graphene in active elements of spintronic devices such as the Das-Datta spin field-effect transistor. Here w...
Article
Tamai et al. discovered an unusual electronic state near the Fermi level at the interface of Cu(111) and a molecular layer of C60, which was initially attributed to C60−Cu interfacial hybridization [Phys. Rev. B 77, 075134 (2008)]. Later on, Yue et al. suggested that the state was due to the reshaping of a two-dimensional electron gas hosted at the...
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Colossal negative magnetoresistance is a well-known phenomenon, notably observed in hole-doped ferromagnetic manganites. It remains a major research topic due to its potential in technological applications. In contrast, topological semimetals show large but positive magnetoresistance, originated from the high-mobility charge carriers. Here, we show...
Preprint
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Colossal magnetoresistance (MR) is a well-known phenomenon, notably observed in hole-doped ferromagnetic manganites. It remains a major research topic due to its potential in technological applications. Though topological semimetals also show large MR, its origin and nature are completely different. Here, we show that in the highly electron doped r...
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Recently the graphene-SiC interface has emerged as a versatile platform for the epitaxy of otherwise unstable, monoelemental, two-dimensional (2D) layers via intercalation. Intrinsically capped into a van der Waals heterostructure with overhead graphene, they compose a new class of quantum materials with striking properties contrasting their parent...
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Artificial graphene based on molecular networks enables the creation of novel 2D materials with unique electronic and topological properties. Landau quantization has been demonstrated by CO molecules arranged on the two-dimensional electron gas on Cu(111) and the observation of electron quantization may succeed based on the created gauge fields. Re...
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The formation of large polarons has been proposed as reason for the high defect tolerance, low mobility, low charge carrier trapping, and low nonradiative recombination rates of lead halide perovskites. Recently, direct evidence for large-polaron formation has been reported from a 50% effective mass enhancement in angle-resolved photoemission of Cs...
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Few-layer graphene on β-SiC(001) functionalized with phenazine dye Neutral Red by means of diazonium chemistry has been studied using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, photoemission electron microscopy, scanning tunneling microscopy, and density functional theory calculations. The experimental data reveal...
Article
Cleaning the n-GaAs surface with low-energy Ar⁺ ions, required in X-ray photoelectron spectroscopy (XPS), has been recently shown to drastically change the core-level binding energies (BEs) of the irradiated surface layer, which prevents the diagnostics of the n-GaAs based semiconductors by the ordinary XPS. Synchrotron-based XPS measurements and m...
Article
The electronic structure and chemical composition of the n-GaAs surface after implantation of N2⁺ ions with energy Ei = 3000 eV and fluence Q ∼ 3 × 10¹⁵ cm⁻² were studied by synchrotron-based X-ray photoelectron spectroscopy to clarify effects of low-energy nitrogen ion implantation on A3B5 semiconductor surfaces. Conversion of the conductivity typ...
Preprint
Enhanced magnetism has recently been reported for the topological-insulator/ferromagnet interface Bi$_2$Se$_3$/EuS with Curie temperatures claimed to be raised above room temperature from the bulk EuS value of 16 K. Here we investigate the analogous interface Bi$_2$Se$_3$/EuSe. EuSe is a low-temperature layered ferrimagnet that is particularly sens...
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New developments in the field of topological matter are often driven by materials discovery, including novel topological insulators, Dirac semimetals, and Weyl semimetals. In the last few years, large efforts have been made to classify all known inorganic materials with respect to their topology. Unfortunately, a large number of topological materia...
Article
Efficient control over the grain boundaries (GBs) is a vital aspect in optimizing the graphene growth conditions. A number of methods for visualization of GBs were developed for graphene grown on weakly interacting surfaces. Here, we utilize oxygen intercalation to reveal GBs and study their morphology for graphene strongly bound to the cobalt surf...
Article
Enhanced magnetism has recently been reported for the topological-insulator/ferromagnet interface Bi2Se3/EuS with Curie temperatures claimed to be raised above room temperature from the bulk EuS value of 16 K. Here we investigate the analogous interface Bi2Se3/EuSe. EuSe is a low-temperature layered ferrimagnet that is particularly sensitive to ext...
Article
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Proximity to heavy sp -elements is considered promising for reaching a band gap in graphene that could host quantum spin Hall states. The recent report of an induced spin-orbit gap of 0.2 eV in Pb-intercalated graphene detectable by spin-resolved photoemission has spurred renewed interest in such systems (Klimovskikh et al 2017 ACS Nano 11 , 368)....
Article
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At very high doping levels the van Hove singularity in the π* band of graphene becomes occupied and exotic ground states possibly emerge, driven by many-body interactions. Employing a combination of ytterbium intercalation and potassium adsorption, we n dope epitaxial graphene on silicon carbide past the π* van Hove singularity, up to a charge carr...
Article
For hybrid organic-inorganic as well as all-inorganic lead halide perovskites a Rashba effect has been invoked to explain the high efficiency in energy conversion by prohibiting direct recombination. Both a bulk and surface Rashba effect have been predicted. In the valence band of methylammonium (MA) lead bromide a Rashba effect has been reported b...
Article
We present a comparative study of oxygen intercalation under polycrystalline and highly ordered graphene on the Co(0001) surface, which are relevant for magnetic applications. A comprehensive experimental study by means of microscopic and spectroscopic techniques shows that intercalation leads to hole-doping and decoupling of graphene from the stro...
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We show that, although the equilibrium band dispersion of the Shockley-type surface state of two-dimensional Au(111) quantum films grown on W(110) does not deviate from the expected free-electron-like behavior, its nonequilibrium energy-momentum dispersion probed by time- and angle-resolved photoemission exhibits a remarkable kink above the Fermi l...
Article
In-plane heterostructures of hexagonal boron nitride (h-BN) and graphene (Gr) have recently appeared in the focus of material science research owing to their intriguing and tunable electronic properties. However, disclosure of the atomic structure and properties of one-dimensional heterojunctions between Gr and h-BN domains remains a largely unexpl...
Article
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The novel approach was proposed for detailed high-resolution studies of morphology and physico-chemical properties concomitantly at one measurement spot of E. coli bacterial cells culture immobilized onto silicon wafer surface in UHV conditions applying PhotoEmission Electron Microscopy under Hg lamp irradiation. For the E. coli characterization sc...
Article
Poor dielectric properties of GaAs oxides are the drawback of the GaAs-based electronics preventing using these oxides as dielectric layers. The elemental and chemical compositions of the GaAs native oxide layer slightly irradiated by Ar⁺ ions with the fluence Q ~1 ∗ 10¹⁴ ions/cm² have been studied by the synchrotron-based photoelectron spectroscop...
Article
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The mechanism of few-layer graphene growth on the technologically-relevant cubic-SiC/Si(001) substrate is uncovered using high-resolution core-level and angle-resolved photoelectron spectroscopy, low-energy electron microscopy, and micro-spot low-energy electron diffraction. The thickness of the graphitic overlayer supported on the silicon carbide...
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The elemental and chemical compositions throughout the thickness of the GaAs native oxide layer slightly irradiated by Ar⁺ ions have been studied by synchrotron-based photoelectron spectroscopy at different photon energies enabling variation of probing depth. The presence of only two phases was observed: of the gallium oxide Ga2O3 and elementary ar...
Article
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The electronic structure of the well-defined n-GaAs (100) near-surface layer irradiated by an ion beam of the keV energy range has been studied by synchrotron-based photoelectron spectroscopy. Conversion of the conductivity type from n into p has been revealed in the irradiated layer several nm thick, thus resulting in the junction formation. The e...
Preprint
Recrystallization of bulk materials is a well-known phenomenon, which is widely used in commercial manufacturing. However, for low-dimensional materials like graphene this process still remains an unresolved puzzle. Thus, understanding of the underlying mechanisms and the required conditions for recrystallization in low dimensions is essential for...
Article
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Detailed information on GaAs oxide properties is important for solving the problem of passivating and dielectric layers in the GaAs-based electronics. The elemental and chemical compositions of the native oxide layer grown on the atomically clean surface of an n-GaAs (100) wafer etched by Ar⁺ ions have been studied by synchrotron-based photoelectro...
Article
Full-text available
Poor dielectric properties of GaAs oxides are the drawback of the GaAs-based electronics preventing using these oxides as dielectric layers. The elemental and chemical compositions of the GaAs native oxide layer slightly irradiated by Ar⁺ ions with the fluence Q ~1 ∗ 10¹⁴ ions/cm² have been studied by the synchrotron-based photoelectron spectroscop...
Article
Electronic 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 3d, Cs 4d, Cs 5p) under synchrotron excitation were meas...
Article
The local chemical surface composition of unsupported mixed solid NaCl/Na2SO4 aerosols (d~70 nm) is studied by X-ray photoelectron spectroscopy. The solid aerosols are generated by drying of aqueous droplets containing mixtures of the two salts in different mole fractions. The mole fraction of these salts is found to deviate at the solid aerosol su...
Article
Titanium carbide attracts growing interest as a substrate for graphene growth and as a component of the composite carbon materials for supercapacitors, an electrode material for metal-air batteries. For all these applications, the surface chemistry of titanium carbide is highly relevant and being, however, insufficiently explored especially at atom...
Article
Full-text available
Detailed information on GaAs oxide properties is important for solving the problem of passivating and dielectric layers in the GaAs- based electronics. The elemental and chemical compositions of the native oxide layer grown on the atomically clean surface of an n-GaAs (100) wafer etched by Ar+ ions have been studied by synchrotron-based photoelectr...
Article
Full-text available
In this work, we present a model of the surface states of nonsymmorphic semimetals. These are derived from surface mass terms that lift the high degeneracy imposed in the band structure by the nonsymmorphic bulk symmetries. Reflecting the reduced symmetry at the surface, the bulk bands are strongly modified. This leads to the creation of two-dimens...
Preprint
In this work, we present a model of the surface states of nonsymmorphic semimetals. These are derived from surface mass terms that lift the high degeneracy imposed in the band structure by the nonsymmorphic bulk symmetries. Reflecting the reduced symmetry at the surface, the bulk bands are strongly modified. This leads to the creation of two-dimens...
Article
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To enhance the spin–orbit interaction in graphene by a proximity effect without compromising the quasi-free-standing dispersion of the Dirac cones means balancing the opposing demands for strong and weak graphene–substrate interaction. So far, only the intercalation of Au under graphene/Ni(1 1 1) has proven successful, which was unexpected since gr...
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Transmission of low-energetic electrons through two-dimensional materials leads to unique scattering resonances. These resonances contribute to photoemission from occupied bands where they appear as strongly dispersive features of suppressed photoelectron intensity. Using angle-resolved photoemission we have systematically studied scattering resona...
Article
Electronic structure has been studied in lightly electron doped correlated spin-orbit insulator Sr$_2$IrO$_4$ by angle-resolved photoelectron spectroscopy. We have observed coexistence of the lower Hubbard band and the in-gap band, the momentum dependence of the latter traces that of the band calculations without on-site Coulomb repulsion. The in-g...
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Topologically nontrivial states reveal themselves in strongly spin-orbit coupled systems by Dirac cones. However, their appearance is not a sufficient criterion for a topological phase. In topological insulators, where these states protect surface metallicity, they are straightforwardly assigned based on bulk-boundary correspondence. On metals, whe...
Article
Regardless of the widely accepted opinion that there is no Raman signal from single-layer graphene when it is strongly bonded to the metal surface, we present Raman spectra of graphene monolayer on the Ni(111) and Co(0001) substrates. High binding energy of carbon to these surfaces allows formation of lattice-matched (1 × 1) structures where graphe...
Article
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The core-level and valence band electronic structure of the well-defined near-surface layer of n-GaAs (100) has been studied by synchrotron-based high-resolution photoelectron spectroscopy before and after modification of the layer by an Ar+ ion beam in the 1.5 - 2.5 keV energy range. Conversion of the conductivity type from n into p has been revea...
Article
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Increasing the magnetic data recording density requires reducing the size of the individual memory elements of a recording layer as well as employing magnetic materials with temperature-dependent functionalities. Therefore, it is predicted that the near future of magnetic data storage technology involves a combination of energy-assisted recording o...
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Materials harbouring exotic quasiparticles, such as massless Dirac and Weyl fermions, have garnered much attention from physics and material science communities due to their exceptional physical properties such as ultra-high mobility and extremely large magnetoresistances. Here, we show that the highly stable, non-toxic and earth-abundant material,...
Article
We reinvestigate the putative giant spin splitting at the surface of SrTiO$_3$ reported by Santander-Syro $et~al.$ [Nature Mat. 13, 1085 (2014)]. Our spin- and angle-resolved photoemission experiments on (001) oriented surfaces supporting a two-dimensional electron liquid with high carrier density show no detectable spin polarization in the photocu...
Article
Photoelectron spectroscopy in combination with piezoforce microscopy reveals that the helicity of Rashba bands is coupled to the nonvolatile ferroelectric polarization of GeTe(111). A novel surface Rashba band is found and fingerprints of a bulk Rashba band are identified by comparison with density functional theory calculations.
Article
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Intercalation of Au can produce giant Rashba-type spin-orbit splittings in graphene but this has not yet been achieved on a semiconductor substrate. For graphene/SiC(0001), Au intercalation yields two phases with different doping. Here, we report the preparation of an almost pure p-type graphene phase after Au intercalation. We observe a 100 meV Ra...
Article
Trilayer graphene exhibits exceptional electronic properties that are of interest both for fundamental science and for technological applications. The ability to achieve a high on-off current ratio is the central question in this field. Here, we propose a simple method to achieve a current on-off ratio of 104 by opening a transport gap in Bernal st...
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Spin and pseudospin in graphene are known to interact under enhanced spin-orbit interaction giving rise to an in-plane Rashba spin texture. Here we show that Au-intercalated graphene on Fe(110) displays a large (∼230 meV) bandgap with out-of-plane hedgehog-type spin reorientation around the gapped Dirac point. We identify two causes responsible. Fi...
Article
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The interface of graphene with ferromagnets is highly relevant for spintronics, because graphene on Co(0001) shows a largely intact Dirac cone and strong hybridization with Co 3d states breaking the sublattice symmetry that had been considered mutually exclusive. Here we show by spin- and angle-resolved photoemission that the Dirac cone and Dirac p...
Article
By angle- and spin-resolved photoemission we have studied electronic structure and spin-orbit splitting in graphene/Ni(111) intercalated with alloy of high spin-orbit materials Bi and Au. Results are compared to ultimate cases of (i) graphene/Ni intercalated only with Au which shows giant Rashba splitting ( 100 meV) and (ii) graphene/Ni intercalate...
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The interatomic interaction and chemical state of elements in amorphous multilayered (Co45Fe45Zr10/a-Si)40 and (Co45Fe45Zr10/SiO2)32 nanostructures with different interlayers have been investigated by X-ray photoelectron spectroscopy using synchrotron radiation. The results of X-ray photoelectron spectroscopy investigations have demonstrated that,...
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We analyze the strong hexagonal warping of the Dirac cone of Bi2Te3 by angle-resolved photoemission. Along ΓM, the dispersion deviates from a linear behavior meaning that the Dirac cone is warped outwards and not inwards. We show that this introduces an anisotropy in the lifetime broadening of the topological surface state which is larger along ΓK....
Article
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Understanding the spin-texture behaviour of boundary modes in ultrathin topological insulator films is critically essential for the design and fabrication of functional nanodevices. Here, by using spin-resolved photoemission spectroscopy with p-polarized light in topological insulator Bi2Se3 thin films, we report tunnelling-dependent evolution of s...
Article
The electronic structure of the n-GaN(0001) and Alx Ga1 − x N(0001) (x = 0.16, 0.42) surfaces and the Ba/n-GaN and Ba/AlGaN interfaces is subjected to in situ photoemission investigations in the submonolayer Ba coverage range. The photoemission spectra of the valence band and the spectra of the surface states and the core 3d level of Ga, the 2p lev...
Article
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The atomic structure of the cubic-SiC(001) surface during ultra-high vacuum graphene synthesis has been studied using scanning tunneling microscopy (STM) and low-energy electron diffraction. Atomically resolved STM studies prove the synthesis of a uniform, millimeter-scale graphene overlayer consisting of nanodomains rotated by ±13.5° relative to t...
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The Ir(111) surface is known to host a surface state with a giant spin-orbit splitting due to the Rashba effect. This surface state is stable even in air when Ir is protected with an epitaxial graphene overlayer. In the present paper, we reveal an effect allowing one to tune the binding energy of this spin-split surface state up and down and demons...
Article
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The paper sums up a theoretical and experimental investigation of the influence of the spin–orbit coupling in W(110) on the spin structure of electronic states in deposited Au and Cu monolayers. Angle-resolved photoemission spectroscopy reveals that in the case of monolayers of Au and Cu spin–orbit split bands are formed in a surface-projected gap...
Article
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The spin-orbit splitting of graphene π states can be strongly enhanced by external influences such as corrugation or proximity to heavier atoms. Here we investigate experimentally and theoretically whether such strong enhancement is possible for graphene on SiC(0001). By spin- and angle-resolved photoemission we found for two independently grown sa...
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Quantitative understanding of the relationship between quantum tunneling and Fermi surface spin polarization is key to device design using topological insulator surface states. By using spin-resolved photoemission spectroscopy with p-polarized light in topological insulator Bi2Se3 thin films across the metal-to-insulator transition, we observe that...
Article
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A modification of the contact of graphene with ferromagnetic electrodes in a model of the graphene spin filter allowing restoration of the graphene electronic structure is proposed. It is suggested for this aim to intercalate into the interface between the graphene and the ferromagnetic (Ni or Co) electrode a Au monolayer to block the strong intera...
Article
The atomic and electronic structure of graphene synthesized on commercially available cubic-SiC(001)/Si(001) wafers have been studied by low energy electron microscopy (LEEM), scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and angle resolved photoelectron spectroscopy (ARPES). LEEM and STM data prove the wafer-scale co...
Article
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The electronic structure and phase composition of amorphous multilayered nanostructures (Co45Fe45Zr10/a-Si)40 and (Co45Fe45Zr10/SiO2)32 have been investigated by means of the X-ray absorption near-edge structure (XANES) technique, which is the most sensitive and useful in investigation of the chemical environment of elements in multicomponent nanos...
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The helical Dirac fermions at the surface of topological insulators show a strong circular dichroism which has been explained as being due to either the initial-state spin angular momentum, the initial-state orbital angular momentum, or the handedness of the experimental setup. All of these interpretations conflict with our data from Bi_{2}Te_{3} w...
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Graphene grown catalytically on Ir(111) shows a large substrate-induced spin-orbit splitting of Δso∼50 meV in spin- and angle-resolved photoemission. Its origin is hybridization as revealed by large gaps in the π band. Reducing the growth temperature results in a very large splitting of the Dirac cone, which is found to be of geometric origin and a...
Article
This paper reports on a study of the process of Al intercalation underneath a graphene monolayer formed on the Ni(111) surface by propylene cracking. Graphene formed on Ni(111) is known to be strongly coupled to the substrate; however, we have been able to show that Al intercalation underneath a graphene monolayer eventually results in blocking of...
Article
A synchrotron-radiation photoemission spectroscopy is applied to the clean and Ba-deposited AlGaN(0001) surfaces to investigate the interface electronic structure relevant to both the surface states and an electron accumulation layer and to clarify their origins. Valence-band photoemission and Ga 3d, Al 2p, Ba 4d core level spectra of AlxGa1-xN (x=...
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magnified image The topological surface state of Bi 2 Te 3 leads to high photoemisson intensity from its Dirac point. This allows us to investigate the effect of larger amounts of deposited Fe than previously achieved for Bi 2 Se 3 . The Dirac point is shown to stay intact up to at least a monolayer showing the robustness of the topological state t...