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131 results on '"Usachov, D."'

1. Insight into the electronic structure of the centrosymmetric skyrmion magnet GdRu$_2$Si$_2$

Author

Eremeev, S. V., Glazkova, D., Poelchen, G., Kraiker, A., Ali, K., Tarasov, A. V., Schulz, S., Kliemt, K., Chulkov, E. V., Stolyarov, V. S., Ernst, A., Krellner, C., Usachov, D. Yu., and Vyalikh, D. V.

Subjects
Condensed Matter - Materials Science
Abstract

The discovery of a square magnetic-skyrmion lattice in GdRu$_2$Si$_2$, with the smallest so far found skyrmion diameter and without a geometrically frustrated lattice, has attracted significant attention, particularly for potential applications in memory devices and quantum computing. In this work, we present a comprehensive study of surface and bulk electronic structures of GdRu$_2$Si$_2$ by utilizing momentum-resolved photoemission (ARPES) measurements and first-principles calculations. We show how the electronic structure evolves during the antiferromagnetic transition when a peculiar helical order of 4$f$ magnetic moments within the Gd layers sets in. A nice agreement of the ARPES-derived electronic structure with the calculated one has allowed us to characterize the features of the Fermi surface (FS), unveil the nested region along the $k_z$ at the corner of the 3D FS, and reveal their orbital compositions. Our findings suggest that the Ruderman-Kittel-Kasuya-Yosida interaction plays a decisive role in stabilizing the spiral-like order of Gd 4$f$ moments responsible for the skyrmion physics in GdRu$_2$Si$_2$. Our results provide a deeper understanding of electronic and magnetic properties of this material, which is crucial for predicting and developing novel skyrmion-based devices., Comment: 13 pages, 8 figures

Published
2023
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3. Factors influencing the energy gap in topological states of antiferromagnetic MnBi$_2$Te$_4$

Author

Shikin, A. M., Makarova, T. P., Eryzhenkov, A. V., Usachov, D. Yu., Estyunin, D. A., Glazkova, D. A., Klimovskikh, I. I., Rybkin, A. G., and Tarasov, A. V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The experimentally measured angle-resolved photoemission dispersion maps for MnBi$_{2}$Te$_{4}$ samples, which show different energy gaps at the Dirac point (DP), are compared with the results of theoretical calculations to find the conditions for the best agreement between theory and experiment. We have analyzed different factors which influence the Dirac gap width: (i) the surface van der Waals (SvdW) distance between the first and second septuple layers (SLs), (ii) the magnetic moment on Mn atoms, (iii) the spin-orbit coupling (SOC) strength for the surface Te and Bi atoms and related changes in the localization of the topological surface states (TSSs). It was shown that all these factors may change the gap width at the DP in a wide range from 5 to $\sim$90~meV. We show that the Dirac gap variation is mainly determined by the corresponding changes in the TSSs spatial distribution. The best agreement between the presented experimental data (with the Dirac gaps between $\sim$15 and 55~meV) and the calculations takes place for a slightly compressed SvdW interval (of about -3.5~\% compared to the bulk value) with modified SOC for surface atoms (that can occur in the presence of various defects in the near-surface region). We show that upon changing the values of the SvdW interval and surface SOC strength the TSSs spatial distribution shifts between the SLs with opposite magnetizations, which leads to a non-monotonic change in the Dirac gap size.

Published
2022

5. Observation of a cubic Rashba effect in the surface spin structure of rare-earth ternary materials

Author

Usachov, D. Yu., Nechaev, I. A., Poelchen, G., Güttler, M., Krasovskii, E. E., Schulz, S., Generalov, A., Kliemt, K., Kraiker, A., Krellner, C., Kummer, K., Danzenbächer, S., Laubschat, C., Weber, A. P., Chulkov, E. V., Santander-Syro, A. F., Imai, T., Miyamoto, K., Okuda, T., and Vyalikh, D. V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Strongly Correlated Electrons
Abstract

Spin-orbit interaction and structure inversion asymmetry in combination with magnetic ordering is a promising route to novel materials with highly mobile spin-polarized carriers at the surface. Spin-resolved measurements of the photoemission current from the Si-terminated surface of the antiferromagnet TbRh2Si2 and their analysis within an ab initio one-step theory unveil an unusual triple winding of the electron spin along the fourfold-symmetric constant energy contours of the surface states. A two-band k.p model is presented that yields the triple winding as a cubic Rashba effect. The curious in-plane spin-momentum locking is remarkably robust and remains intact across a paramagnetic-antiferromagnetic transition in spite of spin-orbit interaction on Rh atoms being considerably weaker than the out-of-plane exchange field due to the Tb 4f moments., Comment: 7 pages, 3 figures

Published
2020
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6. Boron nitride monolayer growth on vicinal Ni(111) surfaces systematically studied with a curved crystal

Author

Fernandez, L., Makarova, A. A., Laubschat, C., Vyalikh, D. V., Usachov, D. Yu., Ortega, J. E., and Schiller, F.

Subjects
Condensed Matter - Materials Science
Abstract

The structural and electronic properties of hexagonal boron nitride (hBN) grown on stepped Ni surfaces are systematically investigated using a cylindrical Ni crystal as a tunable substrate. Our experiments reveal homogeneous hBN monolayer coating of the entire Ni curved surface, which in turn undergoes an overall faceting. The faceted system is defined by step-free hBN/Ni(111) terraces alternating with strongly tilted hBN/Ni(115) or hBN/Ni(110) nanostripes, depending on whether we have A-type or B-type vicinal surfaces, respectively. Such deep substrate self-organization is explained by both the rigidity of the hBN lattice and the lack of registry with Ni crystal planes in the vicinity of the (111) surface. The analysis of the electronic properties by photoemission and absorption spectroscopies reveal a weaker hBN/Ni interaction in (110)- and (115)-oriented facets, as well as an upward shift of the valence band with respect to the band position at the hBN/Ni(111) terrace., Comment: 18 pages, 5 figures

Published
2018
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7. Spectroscopic characterization of N = 9 armchair graphene nanoribbons

Author

Senkovskiy, BV, Haberer, D, Usachov, D Yu, Fedorov, AV, Ehlen, N, Hell, M, Petaccia, L, Di Santo, G, Durr, RA, Fischer, FR, and Grüneis, A

Subjects
Physical Sciences, Condensed Matter Physics, angle-resolved photoelectron spectroscopy, graphene, nanoribbons, near edge X-ray absorption fine structure spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Materials Engineering, Nanotechnology, Applied Physics, Chemical sciences, Engineering, Physical sciences
Abstract

We investigate the N = 9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N = 7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum is shifted to lower binding energy by ∼0.6 eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. Our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications.

Published
2017

8. Quasi-freestanding and single-atom thick layer of hexagonal boron nitride as a substrate for graphene synthesis

Author

Usachov, D., Haberer, D., Grüneis, A., Sachdev, H., Preobrajenski, A. B., Adamchuk, V. K., Laubschat, C., and Vyalikh, D. V.

Subjects
Condensed Matter - Materials Science
Abstract

We demonstrate that freeing a single-atom thick layer of hexagonal boron nitride (hbn) from tight chemical bonding to a Ni(111) thin film grown on a W(110) substrate can be achieved by intercalation of Au atoms into the interface. This process has been systematically investigated using angle-resolved photoemission spectroscopy, X-ray photoemission and absorption techniques. It has been demonstrated that the transition of the hbn layer from the "rigid" into the "quasi-freestanding" state is accompanied by a change of its lattice constant. Using chemical vapor deposition, graphene has been successfully synthesized on the insulating, quasi-freestanding hbn monolayer. We anticipate that the in situ synthesized weakly interacting graphene/hbn double layered system could be further developed for technological applications and may provide perspectives for further inquiry into the unusual electronic properties of graphene., Comment: in print in Phys. Rev. B

Published
2010
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13. ESTABLISHING THE NATURE OF KINETIC EFFECTS OF THE HIGH-TEMPERATURE OXIDATION (COMBUSTION) PROCESS OF SOME LIQUID ORGANIC MATTERS BY ACOUSTIC RADIATION.

Author

Tiutiunyk, V. V., Kalugin, V. D., Levterov, A. A., Sydorenko, O. V., Starodubtsev, S. A., and Usachov, D. V.

Subjects
ACOUSTIC radiation, COMBUSTION kinetics, ORGANIC compounds, ACOUSTIC emission, COMBUSTION, PROPERTIES of matter, IGNITION temperature, ORGANIC foods
Abstract

In this article, the results of the study on the physicochemical characteristics of some liquid organic matters on the kinetics of their high-temperature oxidation (combustion) were presented for the first time. These results were obtained by the method of acoustic emission spectrum from heat source. The research results of the amplitude-time characteristics (until cessation of combustion completely) and the frequency response functions (in a given frequency range) of oxidation (combustion) process of liquid organic matters showed that there are following unambiguous dependences: 1) the dependences of the number of the amplitude maximum of the frequency and time spectrum in a given frequency range, as well as of the fractal dimension of the received acoustic signal on the number of carbon atoms in the carbon frame of organic matters and their molar mass; and 2) the dependences of the time of beginning of the combustion (ignition) of primary cloud of organic matters vapors and the final combustion time of the primary cloud of organic matters vapors on the number of carbon atoms in the carbon frame of the organic matters and their partial vapor pressures. The practical aspect of using the results obtained is dictated by the need to develop standard samples of amplitude-time and amplitude-frequency characteristics, depending on the physicochemical and combustible properties of the organic matters. This is necessary for the data bank of the acoustic emission monitoring system to establish a fire hazardous state and make anti-crisis decisions at critical infrastructure facilities. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Insight into the electronic structure of the centrosymmetric skyrmion magnet GdRu2Si2

Author

Eremeev, S. V., primary, Glazkova, D., additional, Poelchen, G., additional, Kraiker, A., additional, Ali, K., additional, Tarasov, A. V., additional, Schulz, S., additional, Kliemt, K., additional, Chulkov, E. V., additional, Stolyarov, V. S., additional, Ernst, A., additional, Krellner, C., additional, Usachov, D. Yu., additional, and Vyalikh, D. V., additional

Published
2023
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24. Insight into the Temperature Evolution of Electronic Structure and Mechanism of Exchange Interaction in EuS

Author

Fedorov, A. V., primary, Poelchen, G., additional, Eremeev, S. V., additional, Schulz, S., additional, Generalov, A., additional, Polley, C., additional, Laubschat, C., additional, Kliemt, K., additional, Kaya, N., additional, Krellner, C., additional, Chulkov, E. V., additional, Kummer, K., additional, Usachov, D. Yu., additional, Ernst, A., additional, and Vyalikh, D. V., additional

Published
2021
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25. Classical and cubic Rashba effect in the presence of in-plane 4f magnetism at the iridium silicide surface of the antiferromagnet GdIr2Si2

Author

Schulz, S., primary, Vyazovskaya, A. Yu., additional, Poelchen, G., additional, Generalov, A., additional, Güttler, M., additional, Mende, M., additional, Danzenbächer, S., additional, Otrokov, M. M., additional, Balasubramanian, T., additional, Polley, C., additional, Chulkov, E. V., additional, Laubschat, C., additional, Peters, M., additional, Kliemt, K., additional, Krellner, C., additional, Usachov, D. Yu., additional, and Vyalikh, D. V., additional

Published
2021
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26. Photoelectron diffraction for probing valency and magnetism of 4f -based materials: A view on valence-fluctuating EuIr2Si2

Author

Usachov, D. Yu., primary, Tarasov, A. V., additional, Schulz, S., additional, Bokai, K. A., additional, Tupitsyn, I. I., additional, Poelchen, G., additional, Seiro, S., additional, Caroca-Canales, N., additional, Kliemt, K., additional, Mende, M., additional, Kummer, K., additional, Krellner, C., additional, Muntwiler, M., additional, Li, Hang, additional, Laubschat, C., additional, Geibel, C., additional, Chulkov, E. V., additional, Fujimori, S. I., additional, and Vyalikh, D. V., additional

Published
2020
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28. Cubic Rashba Effect in the Surface Spin Structure of Rare-Earth Ternary Materials

Author

Usachov, D. Yu., primary, Nechaev, I. A., additional, Poelchen, G., additional, Güttler, M., additional, Krasovskii, E. E., additional, Schulz, S., additional, Generalov, A., additional, Kliemt, K., additional, Kraiker, A., additional, Krellner, C., additional, Kummer, K., additional, Danzenbächer, S., additional, Laubschat, C., additional, Weber, A. P., additional, Sánchez-Barriga, J., additional, Chulkov, E. V., additional, Santander-Syro, A. F., additional, Imai, T., additional, Miyamoto, K., additional, Okuda, T., additional, and Vyalikh, D. V., additional

Published
2020
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31. Strong spin-orbit coupling in the noncentrosymmetric Kondo lattice

Author

Generalov, A., primary, Falke, J., additional, Nechaev, I. A., additional, Otrokov, M. M., additional, Güttler, M., additional, Chikina, A., additional, Kliemt, K., additional, Seiro, S., additional, Kummer, K., additional, Danzenbächer, S., additional, Usachov, D., additional, Kim, T. K., additional, Dudin, P., additional, Chulkov, E. V., additional, Laubschat, C., additional, Geibel, C., additional, Krellner, C., additional, and Vyalikh, D. V., additional

Published
2018
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33. Atomically precise semiconductor—graphene and hBN interfaces by Ge intercalation

Author

Verbitskiy, N. I., Fedorov, A. V., Profeta, G., Stroppa, A., Petaccia, L., Senkovskiy, B., Nefedov, A., Wöll, C., Usachov, D. Yu., Vyalikh, D. V., Yashina, L. V., Eliseev, A. A., Pichler, T., and Grüneis, A.

Subjects
Surfaces, interfaces and thin films, Two-dimensional materials, Article
Abstract

The full exploration of the potential, which graphene offers to nanoelectronics requires its integration into semiconductor technology. So far the real-world applications are limited by the ability to concomitantly achieve large single-crystalline domains on dielectrics and semiconductors and to tailor the interfaces between them. Here we show a new direct bottom-up method for the fabrication of high-quality atomically precise interfaces between 2D materials, like graphene and hexagonal boron nitride (hBN), and classical semiconductor via Ge intercalation. Using angle-resolved photoemission spectroscopy and complementary DFT modelling we observed for the first time that epitaxially grown graphene with the Ge monolayer underneath demonstrates Dirac Fermions unaffected by the substrate as well as an unperturbed electronic band structure of hBN. This approach provides the intrinsic relativistic 2D electron gas towards integration in semiconductor technology. Hence, these new interfaces are a promising path for the integration of graphene and hBN into state-of-the-art semiconductor technology.

Published
2015
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34. Intercalation synthesis of graphene-capped iron silicide atop Ni(111): Evolution of electronic structure and ferromagnetic ordering

Author

Grebenyuk, G. S., Vilkov, O. Yu., Rybkin, A. G., Gomoyunova, M. V., Senkovskiy, B. V., Usachov, D. Yu., Vyalikh, D. V., Molodtsov, S. L., Pronin, I. I., Grebenyuk, G. S., Vilkov, O. Yu., Rybkin, A. G., Gomoyunova, M. V., Senkovskiy, B. V., Usachov, D. Yu., Vyalikh, D. V., Molodtsov, S. L., and Pronin, I. I.

Abstract

A new method for synthesis of graphene-protected iron silicides has been tested, which consists in formation of graphene on Ni(111) followed by two-step intercalation of the system with Fe and Si. Characterization of the samples was performed in situ by low-energy electron diffraction, angular-resolved photoelectron spectroscopy, core-level photoelectron spectroscopy with synchrotron radiation and magnetic linear dichroism in photoemission of Fe 3p electrons. It is shown, that at 400 degrees C the intercalation of graphene/Ni(111) with iron occurs in a range up to 14 ML. The graphene layer strongly interacts with the topmost Fe atoms and stabilizes the fcc structure of the film. The in-plane ferromagnetic ordering of the film has a threshold nature and arises after the intercalation of 5 ML Fe due to the thickness-driven spin reorientation transition. Subsequent intercalation of graphene/Fe/Ni(111) with Si leads to the formation of the inhomogeneous system consisted of intercalated and nonintercalated areas. The intercalated islands coalesce at 2 ML Si when a Fe-Si solid solution covered with the Fe3Si surface silicide is formed. The Fe3Si silicide is ferromagnetic and has an ordered (root 3 x root 3)R30 degrees structure. The graphene layer is weakly electronically coupled to the silicide phase keeping its remarkable properties ready for use. (C) 2016 Elsevier B.V. All rights reserved.

Published
2017

35. Spectroscopic characterization of N=9 armchair graphene nanoribbons

Author

Senkovskiy, B. V., Haberer, D., Usachov, D. Yu., Fedorov, A. V., Ehlen, N., Hell, M., Petaccia, L., Di Santo, G., Durr, R. A., Fischer, F. R., Grueneis, A., Senkovskiy, B. V., Haberer, D., Usachov, D. Yu., Fedorov, A. V., Ehlen, N., Hell, M., Petaccia, L., Di Santo, G., Durr, R. A., Fischer, F. R., and Grueneis, A.

Abstract

We investigate the N=9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N=7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum is shifted to lower binding energy by approximate to 0.6eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. Our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications.

Published
2017

36. Environmental control of electron-phonon coupling in barium doped graphene

Author

Verbitskiy, N. I., Fedorov, A. V., Tresca, C., Profeta, G., Petaccia, L., Senkovskiy, B. V., Usachov, D. Yu, Vyalikh, D. V., Yashina, L. V., Eliseev, A. A., Pichler, T., Grueneis, A., Verbitskiy, N. I., Fedorov, A. V., Tresca, C., Profeta, G., Petaccia, L., Senkovskiy, B. V., Usachov, D. Yu, Vyalikh, D. V., Yashina, L. V., Eliseev, A. A., Pichler, T., and Grueneis, A.

Abstract

Two-dimensional superconductivity in alkali-and alkaline-Earth-metal doped monolayer graphene has been explained in the framework of electron-phonon coupling (EPC) and experiments yielded superconducting transition temperatures (TC) up to 6 K. In contrast to bulk graphite intercalation compounds, the interface of doped graphene with its environment affects its physical properties. Here we present a novel and well-defined BaC8 interface structure in Ba-doped single-layer graphene on Au and Ge substrates. We use angle-resolved photoemission spectroscopy in combination with ab initio modelling to extract the Eliashberg function and EPC for both substrates. This allows us to quantitatively assess the environmental effects for both Au and Ge substrates on superconductivity in graphene. We show that for semiconducting Ge substrates, the doping level and EPC are higher. Our study highlights that both dopant order and the metallicity of the substrate can be used to control EPC and hence superconductivity.

Published
2016

37. First-principles and angle-resolved photoemission study of lithium doped metallic black phosphorous

Author

Sanna, A., Fedorov, A. V., Verbitskiy, N. I., Fink, J., Krellner, C., Petaccia, L., Chikina, A., Usachov, D. Yu., Grüneis, A., Profeta, G., Sanna, A., Fedorov, A. V., Verbitskiy, N. I., Fink, J., Krellner, C., Petaccia, L., Chikina, A., Usachov, D. Yu., Grüneis, A., and Profeta, G.

Abstract

First principles calculations demonstrate the metallization of phosphorene by means of Li doping filling the unoccupied antibonding pz states. The electron–phonon coupling in the metallic phase is strong enough to eventually lead to a superconducting phase at Tc= 17 K for LiP8 stoichiometry. Using angle-resolved photoemission spectroscopy we confirm that the surface of black phosphorus can be chemically functionalized using Li atoms which donate their 2s electron to the conduction band. The combined theoretical and experimental study demonstrates the semiconductor-metal transition indicating a feasible way to induce a superconducting phase in phosphorene and few-layer black phosphorus.

Published
2016

40. Efficient gating of epitaxial boron nitride monolayers by substrate functionalization

Author

Fedorov, A., Praveen, C. S., Verbitskiy, N. I., Haberer, D., Usachov, D., Vyalikh, D. V., Nefedov, A., Woll, C., Petaccia, L., Piccinin, S., Sachdev, H., Knupfer, M., Buchner, B., Fabris, S., Gruneis, A., Fedorov, A., Praveen, C. S., Verbitskiy, N. I., Haberer, D., Usachov, D., Vyalikh, D. V., Nefedov, A., Woll, C., Petaccia, L., Piccinin, S., Sachdev, H., Knupfer, M., Buchner, B., Fabris, S., and Gruneis, A.

Abstract

Insulating hexagonal boron nitride monolayers (hBN) are best known for being resistant to chemical functionalization. This property makes hBN an excellent substrate for graphene heterostructures, but limits its application as an active element in nanoelectronics where tunable electronic properties are needed. Moreover, the two-dimensional–materials’ community wishes to learn more about the adsorption and intercalation characteristics of alkali metals on hBN, which have direct relevance to several electrochemistry experiments that are envisioned with layered materials. Here we provide results on ionic functionalization of hBN/metal interfaces with K and Li dopants. By combining angle-resolved photoemission spectroscopy (ARPES), x-ray photoelectron spectroscopy, and density functional theory calculations, we show that the metallic substrate readily ionizes the alkali dopants and exposes hBN to large electric fields and band-energy shifts. In particular, if hBN is in between the negatively charged substrate and the positive alkali ion, this allows us to directly study, using ARPES, the effects of large electric fields on the electron energy bands of hBN.

Published
2015

42. Efficient gating of epitaxial boron nitride monolayers by substrate functionalization

Author

Fedorov, A., primary, Praveen, C. S., additional, Verbitskiy, N. I., additional, Haberer, D., additional, Usachov, D., additional, Vyalikh, D. V., additional, Nefedov, A., additional, Wöll, C., additional, Petaccia, L., additional, Piccinin, S., additional, Sachdev, H., additional, Knupfer, M., additional, Büchner, B., additional, Fabris, S., additional, and Grüneis, A., additional

Published
2015
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43. Study of the crystal and electronic structure of graphene films grown on 6 H-SiC (0001).

Author

Davydov, V., Usachov, D., Lebedev, S., Smirnov, A., Levitskii, V., Eliseyev, I., Alekseev, P., Dunaevskiy, M., Vilkov, O., Rybkin, A., and Lebedev, A.

Subjects
ELECTRIC properties of materials, ELECTRONIC structure, GRAPHENE, SILICON carbide, CHEMICAL decomposition
Abstract

The structural, chemical, and electronic properties of epitaxial graphene films grown by thermal decomposition of the Si-face of a semi-insulating 6 H-SiC substrate in an argon environment are studied by Raman spectroscopy, atomic-force microscopy, the low-energy electron diffraction method, X-ray photoelectron spectroscopy, angle-resolved photoemission spectroscopy and X-ray absorption spectroscopy at the carbon K edge. It is shown that the results of a systematic integrated study make it possible to optimize the growth parameters and develop a reliable technology for the growth of high-quality single-layer graphene films with a small fraction of bilayer graphene inclusions. [ABSTRACT FROM AUTHOR]

Published
2017
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44. Spectroscopic characterization of N = 9 armchair graphene nanoribbons.

Author

Senkovskiy, B. V., Haberer, D., Usachov, D. Yu., Fedorov, A. V., Ehlen, N., Hell, M., Petaccia, L., Di Santo, G., Durr, R. A., Fischer, F. R., and Grüneis, A.

Subjects
GRAPHENE, CARBON nanotubes, X-ray photoelectron spectroscopy, BINDING energy, PHOTOEMISSION
Abstract

We investigate the N = 9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N = 7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum is shifted to lower binding energy by ∼0.6 eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. Our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications. [ABSTRACT FROM AUTHOR]

Published
2017
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45. Observation of a universal donor-dependent vibrational mode in graphene

Author

Fedorov, A. V., primary, Verbitskiy, N. I., additional, Haberer, D., additional, Struzzi, C., additional, Petaccia, L., additional, Usachov, D., additional, Vilkov, O. Y., additional, Vyalikh, D. V., additional, Fink, J., additional, Knupfer, M., additional, Büchner, B., additional, and Grüneis, A., additional

Published
2014
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50. Electronic properties of hydrogenated quasi‐free‐standing graphene

Author

Haberer, D., primary, Petaccia, L., additional, Wang, Y., additional, Quian, H., additional, Farjam, M., additional, Jafari, S. A., additional, Sachdev, H., additional, Federov, A. V., additional, Usachov, D., additional, Vyalikh, D. V., additional, Liu, X., additional, Vilkov, O., additional, Adamchuk, V. K., additional, Irle, S., additional, Knupfer, M., additional, Büchner, B., additional, and Grüneis, A., additional

Published
2011
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