Role of electron-phonon interactions versus electron-electron interactions in the broadening mechanism of the electron and hole linewidths in bulk Be

Sklyadneva, I. Yu.; Chulkov, Eugene V.; Schöne, Wolf-Dieter; Silkin, Viatcheslav M.; Keyling, Robert; Echenique, Pedro M.

doi:10.1103/physrevb.71.174302

Cited by 31 publications

(36 citation statements)

References 54 publications

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“…The Coulomb pseudo-potential  m was fixed to 0.13, a typical value for metallic samples. From equation (5) we obtain λ ep =0.64(1) for ReBe 22 , almost three times larger than the reported value for elemental Be (0.21) [32]. By using this value, finally, the band-structure DOS N band (ò F ) can be estimated from the relation…”

Section: Specific Heatmentioning

confidence: 79%

Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor

et al. 2019

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In search of the origin of superconductivity (SC) in diluted rhenium superconductors and their significantly enhanced T c compared to pure Be (0.026 K), we investigated the intermetallic ReBe 22 compound, mostly by means of muon-spin rotation/relaxation (μSR). At a macroscopic level, its bulk SC (with T c =9.4 K) was studied via electrical resistivity, magnetization, and heat-capacity measurements. The superfluid density, as determined from transverse-field μSR and electronic specific-heat measurements, suggest that ReBe 22 is a fully-gapped superconductor with some multigap features. The larger gap value, D = 1.78 l 0 T k B c , with a weight of almost 90%, is slightly higher than that expected from the BCS theory in the weak-coupling case. The multigap feature, rather unusual for an almost elemental superconductor, is further supported by the field-dependent specific-heat coefficient, the temperature dependence of the upper critical field, as well as by electronic bandstructure calculations. The absence of spontaneous magnetic fields below T c , as determined from zero-field μSR measurements, indicates a preserved time-reversal symmetry in the superconducting state of ReBe 22 . In general, we find that a dramatic increase in the density of states at the Fermi level and an increase in the electron-phonon coupling strength, both contribute to the highly enhanced T c value of ReBe 22 .

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Section: Specific Heatmentioning

confidence: 79%

Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor

et al. 2019

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“…The theoretical value of l at E F was found to be 0.9 in good agreement with the available data. In any event, the coupling is much stronger than in bulk Be for which l ¼ 0:21À0:23 (theory, [67,68] The C surface states of Mg(0001) and Al(001) have a rather different character from those of the noble metal (111) surfaces and of Be(0001). Both reside in a narrow projected bandgap and penetrate deeply into the bulk.…”

Section: Be(0001)mentioning

confidence: 99%

“…Another important finding was that the low-and middle-energy phonons are more involved in the scattering processes of electrons than the high-energy phonon modes unlike the case of bulk Al, as well as other simple metals Be and Mg, where the lower energy part of the phonon spectrum is strongly suppressed by eÀph matrix elements [27,61,[68][69][70].…”

Section: Be(0001)mentioning

confidence: 99%

Electron–Phonon Interaction at Interfaces

Hofmann

Chulkov

Sklyadneva

2010

Dynamics at Solid State Surfaces and Interfaces

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Many-body effects and their interplay are at the heart of some of the most interesting problems in condensed matter physics, and frequently the simultaneous presence of different effects is found in complex materials. The electron-phonon (eÀph) interaction is one such effect that limits the lifetime of excited electrons (or holes) and has long been studied because of its role in many phenomena, from electrical conductivity to electronic heat capacity and BCS-type superconductivity. Several experimental techniques such as tunneling spectroscopy or heat capacity measurements have provided information on the electron-phonon coupling strength averaged over the bulk Fermi surface of metals [1].Experimentally, recent advances in angle-resolved photoemission (ARPES) have opened the opportunity for a study of many-body effects in unprecedented detail. Most importantly, studies are not confined to averages over the Fermi surface but detailed information about the energy and k-dependence of the interaction has come within reach. This permits, for instance, to establish the symmetry of the superconducting gap in novel superconductors [2,3].The eÀph interaction stands out as a fundamental many-body process that can be tested by both experimental and theoretical methods. Much has been learned by studying the eÀph coupling on carefully chosen electronic surface states, for which good arguments can be made for the eÀph interaction to be the only many-body effect giving rise to a bosonic spectroscopic signature. Surface states have also played an important role because they have, as do the states in the cuprates, a merely two-dimensional dispersion, an essential prerequisite for the analysis of ARPES data.In the most simple picture, the eÀph coupling changes the dispersion and the lifetime of the electronic states in a material. This situation is illustrated in Figure 7.1a. Very close to the Fermi level, within a typical phonon energy hv D , the dispersion is renormalized such that it is flatter at the Fermi energy. Consequently, the effective mass of the electrons at the Fermi level and the density of states are

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“…1, 31 As regards the Be(1010) surface, a great deal of experimental information is now available on the e-ph coupling of two Shockley-type surface electronic states at the surface Brillouin zone (SBZ) boundary (the A point). Several experimental studies [19][20][21]24 using both the temperature dependence of the photoemission linewidth and the renormalization of the surface-state dispersion at F revealed that the strength of the e-ph interaction in these surface states was different.…”

Section: Introductionmentioning

confidence: 99%

Electron-phonon coupling in surface electronic states on Be(101¯0)

et al. 2011

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We present an ab initio study of the electron-phonon interaction in surface electronic states on Be(1010). The calculations based on density-functional theory were carried out using a linear-response approach and a mixed-basis pseudopotential method. It is shown that the strength of the electron-phonon coupling is sensitive to the energy and momentum position of an electronic state and varies from 0.16 to 0.54. The difference in the electron-phonon interaction of two Shockley-type surface states at A can be understood on the basis of their different energy positions in the projected band gap. Previous experiments addressing the electron-phonon coupling strength of these two surface states are discussed in light of our theoretical findings.

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Role of electron-phonon interactions versus electron-electron interactions in the broadening mechanism of the electron and hole linewidths in bulk Be

Cited by 31 publications

References 54 publications

Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor

Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor

Electron–Phonon Interaction at Interfaces

Electron-phonon coupling in surface electronic states on Be(101¯0)

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Role of electron-phonon interactions versus electron-electron interactions in the broadening mechanism of the electron and hole linewidths in bulk Be

Cited by 31 publications

References 54 publications

Enhanced Tc and multiband superconductivity in the fully-gapped ReBe22 superconductor

Enhanced Tc and multiband superconductivity in the fully-gapped ReBe22 superconductor

Electron–Phonon Interaction at Interfaces

Electron-phonon coupling in surface electronic states on Be(101¯0)

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Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor

Enhanced T_c and multiband superconductivity in the fully-gapped ReBe₂₂ superconductor