The Experts below are selected from a list of 4635 Experts worldwide ranked by ideXlab platform
Salvador Miretartes - One of the best experts on this subject based on the ideXlab platform.
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the electron phonon coupling constant for single layer graphene on metal substrates determined from he atom scattering
Physical Chemistry Chemical Physics, 2021Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:Recent theory has demonstrated that the value of the electron–phonon coupling strength λ can be extracted directly from the thermal attenuation (Debye–Waller Factor) of helium atom scattering reflectivity. This theory is here extended to multivalley semimetal systems and applied to the case of graphene on different metal substrates and graphite. It is shown that λ rapidly increases for decreasing graphene–substrate binding strength. Two different calculational models are considered which produce qualitatively similar results for the dependence of λ on binding strength. These models predict, respectively, values of λHAS = 0.89 and 0.32 for a hypothetical flat free-standing single-layer graphene with cyclic boundary conditions. The method is suitable for analysis and characterization of not only the graphene overlayers considered here, but also other layered systems such as twisted graphene bilayers.
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origin of the electron phonon interaction of topological semimetal surfaces measured with helium atom scattering
Journal of Physical Chemistry Letters, 2020Co-Authors: G Benedek, J R Manson, Salvador Miretartes, Adrian Ruckhofer, Wolfgang Ernst, Anton TamtoglAbstract:He atom scattering has been demonstrated to be a sensitive probe of the electron-phonon interaction parameter λ at metal and metal-overlayer surfaces. Here it is shown that the theory linking λ to the thermal attenuation of atom scattering spectra (the Debye-Waller Factor) can be applied to topological semimetal surfaces, such as the quasi-one-dimensional charge-density-wave system Bi(114) and the layered pnictogen chalcogenides. The electron-phonon coupling, as determined for several topological insulators belonging to the class of bismuth chalcogenides, suggests a dominant contribution of the surface quantum well states over the Dirac electrons in terms of λ.
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electron phonon coupling strength at metal surfaces directly determined from the helium atom scattering debye waller Factor
Journal of Physical Chemistry Letters, 2016Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:A new quantum-theoretical derivation of the elastic and inelastic scattering probability of He atoms from a metal surface, where the energy and momentum exchange with the phonon gas can occur only through the mediation of the surface free-electron density, shows that the Debye-Waller exponent is directly proportional to the electron-phonon mass coupling constant λ. The comparison between the values of λ extracted from existing data on the Debye-Waller Factor for various metal surfaces and the λ values known from literature indicates a substantial agreement, which opens the possibility of directly extracting the electron-phonon coupling strength in quasi-2D conducting systems from the temperature or incident energy dependence of the elastic helium atom scattering intensities.
G Benedek - One of the best experts on this subject based on the ideXlab platform.
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the electron phonon coupling constant for single layer graphene on metal substrates determined from he atom scattering
Physical Chemistry Chemical Physics, 2021Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:Recent theory has demonstrated that the value of the electron–phonon coupling strength λ can be extracted directly from the thermal attenuation (Debye–Waller Factor) of helium atom scattering reflectivity. This theory is here extended to multivalley semimetal systems and applied to the case of graphene on different metal substrates and graphite. It is shown that λ rapidly increases for decreasing graphene–substrate binding strength. Two different calculational models are considered which produce qualitatively similar results for the dependence of λ on binding strength. These models predict, respectively, values of λHAS = 0.89 and 0.32 for a hypothetical flat free-standing single-layer graphene with cyclic boundary conditions. The method is suitable for analysis and characterization of not only the graphene overlayers considered here, but also other layered systems such as twisted graphene bilayers.
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origin of the electron phonon interaction of topological semimetal surfaces measured with helium atom scattering
Journal of Physical Chemistry Letters, 2020Co-Authors: G Benedek, J R Manson, Salvador Miretartes, Adrian Ruckhofer, Wolfgang Ernst, Anton TamtoglAbstract:He atom scattering has been demonstrated to be a sensitive probe of the electron-phonon interaction parameter λ at metal and metal-overlayer surfaces. Here it is shown that the theory linking λ to the thermal attenuation of atom scattering spectra (the Debye-Waller Factor) can be applied to topological semimetal surfaces, such as the quasi-one-dimensional charge-density-wave system Bi(114) and the layered pnictogen chalcogenides. The electron-phonon coupling, as determined for several topological insulators belonging to the class of bismuth chalcogenides, suggests a dominant contribution of the surface quantum well states over the Dirac electrons in terms of λ.
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theory of atom scattering from surface phonons basic concepts and temperature effects
2018Co-Authors: G Benedek, J P ToenniesAbstract:The reflection coefficient determining the inelastic scattered intensity is defined and analysed theoretically. Various approximations including the Born approximation, the Distorted-Wave Born approximation (DWBA), the GR method and the eikonal approximation are discussed and illustrated with examples. From an expression for the DWBA inelastic reflection coefficient for n-phonon processes, Factors determining the relative role of temperature for multiphonon processes and one-phonon scattering are analysed. Several approximate expressions for the Debye-Waller Factor are derived and used to define experimental criteria favouring one-phonon scattering. Most of the examples dealt with are for insulator surfaces. Chapter 8 then describes the scattering theory for metal and semiconductor surfaces.
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electron phonon coupling strength at metal surfaces directly determined from the helium atom scattering debye waller Factor
Journal of Physical Chemistry Letters, 2016Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:A new quantum-theoretical derivation of the elastic and inelastic scattering probability of He atoms from a metal surface, where the energy and momentum exchange with the phonon gas can occur only through the mediation of the surface free-electron density, shows that the Debye-Waller exponent is directly proportional to the electron-phonon mass coupling constant λ. The comparison between the values of λ extracted from existing data on the Debye-Waller Factor for various metal surfaces and the λ values known from literature indicates a substantial agreement, which opens the possibility of directly extracting the electron-phonon coupling strength in quasi-2D conducting systems from the temperature or incident energy dependence of the elastic helium atom scattering intensities.
J R Manson - One of the best experts on this subject based on the ideXlab platform.
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the electron phonon coupling constant for single layer graphene on metal substrates determined from he atom scattering
Physical Chemistry Chemical Physics, 2021Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:Recent theory has demonstrated that the value of the electron–phonon coupling strength λ can be extracted directly from the thermal attenuation (Debye–Waller Factor) of helium atom scattering reflectivity. This theory is here extended to multivalley semimetal systems and applied to the case of graphene on different metal substrates and graphite. It is shown that λ rapidly increases for decreasing graphene–substrate binding strength. Two different calculational models are considered which produce qualitatively similar results for the dependence of λ on binding strength. These models predict, respectively, values of λHAS = 0.89 and 0.32 for a hypothetical flat free-standing single-layer graphene with cyclic boundary conditions. The method is suitable for analysis and characterization of not only the graphene overlayers considered here, but also other layered systems such as twisted graphene bilayers.
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origin of the electron phonon interaction of topological semimetal surfaces measured with helium atom scattering
Journal of Physical Chemistry Letters, 2020Co-Authors: G Benedek, J R Manson, Salvador Miretartes, Adrian Ruckhofer, Wolfgang Ernst, Anton TamtoglAbstract:He atom scattering has been demonstrated to be a sensitive probe of the electron-phonon interaction parameter λ at metal and metal-overlayer surfaces. Here it is shown that the theory linking λ to the thermal attenuation of atom scattering spectra (the Debye-Waller Factor) can be applied to topological semimetal surfaces, such as the quasi-one-dimensional charge-density-wave system Bi(114) and the layered pnictogen chalcogenides. The electron-phonon coupling, as determined for several topological insulators belonging to the class of bismuth chalcogenides, suggests a dominant contribution of the surface quantum well states over the Dirac electrons in terms of λ.
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electron phonon coupling strength at metal surfaces directly determined from the helium atom scattering debye waller Factor
Journal of Physical Chemistry Letters, 2016Co-Authors: G Benedek, J R Manson, Salvador MiretartesAbstract:A new quantum-theoretical derivation of the elastic and inelastic scattering probability of He atoms from a metal surface, where the energy and momentum exchange with the phonon gas can occur only through the mediation of the surface free-electron density, shows that the Debye-Waller exponent is directly proportional to the electron-phonon mass coupling constant λ. The comparison between the values of λ extracted from existing data on the Debye-Waller Factor for various metal surfaces and the λ values known from literature indicates a substantial agreement, which opens the possibility of directly extracting the electron-phonon coupling strength in quasi-2D conducting systems from the temperature or incident energy dependence of the elastic helium atom scattering intensities.
A V Nikolaev - One of the best experts on this subject based on the ideXlab platform.
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ab initio based description of the unusual increase of the electric field gradient with temperature at ti sites in rutile tio 2
Physical Review B, 2020Co-Authors: A V Nikolaev, N M Chtchelkatchev, A V Bibikov, D A Salamatin, A V TsvyashchenkoAbstract:Combining a precise ab initio electron band structure calculation of the ${\mathrm{TiO}}_{2}$ rutile structure with the temperature evolution of the Ti mean-square displacements, we reproduce a puzzling temperature increase of the electric field gradient at Ti sites in ${\mathrm{TiO}}_{2}$, observed experimentally. Our method employs a procedure of averaging two quadrupole electron density components ($L=2$) inside a sphere vibrating with the Ti nucleus at its center, where the key Factor introducing the temperature dependence is the square root of the Debye-Waller Factor. Although the Debye-Waller Factor always reduces the corresponding Fourier component, in ${\mathrm{TiO}}_{2}$ due to the interplay between terms of opposite signs, it results in a net increase of the whole sum with temperature, leading to the growth of the electric field gradient. Quantitatively, we find that the increase of electric field gradient is only half of the experimental value, which we ascribe to anharmonic effects or a strong oxygen position influence. In addition, our method reproduces the unusual temperature dependence of the asymmetry parameter $\ensuremath{\eta}$, which first decreases with temperature, goes to zero, and then increases.
Stefan Sellner - One of the best experts on this subject based on the ideXlab platform.
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self consistent interpretation of the 2d structure of the liquid au 82 si 18 surface bending rigidity and the debye waller effect
Physical Review Letters, 2010Co-Authors: S Mechler, Peter S Pershan, E Yahel, S E Stoltz, Oleg Shpyrko, Binhua Lin, Mati Meron, Stefan SellnerAbstract:The structural and mechanical properties of 2D crystalline surface phases that form at the surface of liquid eutectic ${\mathrm{Au}}_{82}{\mathrm{Si}}_{18}$ are studied using synchrotron x-ray scattering over a large temperature range. In the vicinity of the eutectic temperature the surface consists of a 2D atomic bilayer crystalline phase that transforms into a 2D monolayer crystalline phase during heating. The latter phase eventually melts into a liquidlike surface on further heating. We demonstrate that the short wavelength capillary wave fluctuations are suppressed due to the bending rigidity of 2D crystalline phases. The corresponding reduction in the Debye-Waller Factor allows for measured reflectivity to be explained in terms of an electron density profile that is consistent with the 2D surface crystals.
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self consistent interpretation of the 2d structure of the liquid au82si18 surface bending rigidity and the debye waller effect
Physical Review Letters, 2010Co-Authors: S Mechler, Peter S Pershan, E Yahel, S E Stoltz, Oleg Shpyrko, Binhua Lin, Mati Meron, Stefan SellnerAbstract:The structural and mechanical properties of 2D crystalline surface phases that form at the surface of liquid eutectic Au{sub 82}Si{sub 18} are studied using synchrotron x-ray scattering over a large temperature range. In the vicinity of the eutectic temperature the surface consists of a 2D atomic bilayer crystalline phase that transforms into a 2D monolayer crystalline phase during heating. The latter phase eventually melts into a liquidlike surface on further heating. We demonstrate that the short wavelength capillary wave fluctuations are suppressed due to the bending rigidity of 2D crystalline phases. The corresponding reduction in the Debye-Waller Factor allows for measured reflectivity to be explained in terms of an electron density profile that is consistent with the 2D surface crystals.
