Lattice vibrations and electron-phonon coupling in superconducting quarternary borocarbides: An inelastic neutron-scattering investigation

Gompf, F.; Reichardt, W.; Schober, H.; Renker, B.; Buchgeister, M.

doi:10.1103/physrevb.55.9058

Cited by 44 publications

(46 citation statements)

References 20 publications

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“…In the phonon DOS for the nonmagnetic sister compound YNi 2 B 2 C a maximum at around 100 meV has been observed in Ref. 15. It has been attributed to the high-frequency B-C bond stretching vibration in accord with theoretical results obtained in frozen phonon calculations at 106 meV for the zonecenter Raman active mode of YNi 2 B 2 C [16].…”

Section: Pcs Of Quasiparticle Excitationssupporting

confidence: 62%

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Point-contact spectroscopy of the antiferromagnetic superconductorHoNi2B2Cin the normal and superconducting state

et al. 2007

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Point-contact (PC) spectroscopy measurements on antiferromagnetic (AF) (TN ≃5.2 K) HoNi2B2C single crystals in the normal and two different superconducting (SC) states (Tc ≃8.5 K and T * c ≃ 5.6 K) are reported. The PC study of the electron-boson(phonon) interaction (EB(P)I) spectral function reveals pronounced phonon maxima at 16, 22 and 34 meV. For the first time the high energy maxima at about 50 meV and 100 meV are resolved. Additionally, an admixture of a crystalline-electric-field (CEF) excitations with a maximum near 10 meV and a 'magnetic' peak near 3 meV are observed. The contribution of the 10-meV peak in PC EPI constant λPC is evaluated as 20-30%, while contribution of the high energy modes at 50 and 100 meV amounts about 10% for each maxima, so the superconductivity might be affected by CEF excitations. The SC gap in HoNi2B2C exhibits a standard single-band BCS-like dependence, but vanishes at T * c ≃ 5.6 K< Tc, with 2∆/kBT * c ≃ 3.9. The strong coupling Eliashberg analysis of the low-temperature SC phase with T * c ≃ 5.6 K ∼ TN, coexisting with the commensurate AF structure, suggests a sizable value of the EPI constant λs ∼ 0.93. We also provide strong support for the recently proposed by us "Fermi surface (FS) separation" scenario for the coexistence of magnetism and superconductivity in magnetic borocarbides, namely, that the superconductivity in the commensurate AF phase survives at a special (nearly isotropic) FS sheet without an admixture of Ho 5d states. Above T * c the SC features in the PC characteristics are strongly suppressed pointing to a specific weakened SC state between T * c and Tc.

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Section: Pcs Of Quasiparticle Excitationssupporting

confidence: 62%

“…2(a) displays the PC EBI function, obtained from the PC spectrum after subtraction of the background. According to the neutron data [15] there is a gap around 40 meV in the phonon DOS, which separates the acoustic and the optic branches. In this energy region a minimum occurs in our PC spectra.…”

Section: Pcs Of Quasiparticle Excitationsmentioning

confidence: 99%

Point-contact spectroscopy of the antiferromagnetic superconductorHoNi2B2Cin the normal and superconducting state

et al. 2007

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“…corresponding generalized phonon density of states with the experimental data extracted from [20]. The agreement with the latter is much better for the calculation using the experimental lattice parameters over the entire energy range and, in particular, for the pronounced peak located around 50 meV in the experimental data.…”

Section: Iv3 Lattice Dynamicssupporting

confidence: 61%

Phonons and electron-phonon coupling in YNi2B2C

et al. 2014

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We present a combined density-functional-perturbation-theory and inelastic neutron scattering study of the lattice dynamical properties of YNi 2 B 2 C. In general, very good agreement was found between theory and experiment for both phonon energies and line widths. Our analysis reveals that the strong coupling of certain low energy modes is linked to the presence of large displacements of the light atoms, i.e. B and C, which is unusual in view of the rather low phonon energies. Specific modes exhibiting a strong coupling to the electronic quasiparticles were investigated as a function of temperature. Their energies and line widths showed marked changes on cooling from room temperature to just above the superconducting transition at T c = 15.2 K. Calculations simulating the effects of temperature allow to model the observed temperature dependence qualitatively.

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“…In this respect, the use of high quality single crystals is invaluable, since the properties of these compounds are often very anisotropic. [22] (curves (a) and (c) ) and electron-quasiparticle spectral functions obtained by point-contact spectroscopy at liquid helium temperatures [23] for non-superconducting LaNi2B2C and superconducting YNi2B2C, respectively. Note the substantial softening of low-frequency phonons in YNi2B2C due to lowering temperature [24].…”

Section: Discussionmentioning

confidence: 99%

“…Comparison between phonon DOS and EQI spectral function for superconducting YNi 2 B 2 C and non-superconducting LaNi 2 B 2 C. It is very instructive to compare the phonon density of states, measured by inelastic neutron scattering, and the EPI (EQI) spectral function, obtained by PCS, for superconducting and non-superconducting compounds (Fig.5). For these we choose the nonmagnetic superconducting compound YNi 2 B 2 C and non-superconducting homologue LaNi 2 B 2 C [22,23]. The phonon spectra measured by neutrons contain three groups of peaks: lowfrequency modes (0-30 meV), middle-frequency group (40-60 meV) and boron high-frequency modes (100-160 meV) [22].…”

Section: Principles Of Pcsmentioning

confidence: 99%

Andreev-Reflection and Point-Contact Spectroscopy of Superconducting Rare Earth Transition Metal Borocarbides

Yanson

2001

Rare Earth Transition Metal Borocarbides (Nitrides): Superconducting, Magnetic and Normal State Properties

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Lattice vibrations and electron-phonon coupling in superconducting quarternary borocarbides: An inelastic neutron-scattering investigation

Cited by 44 publications

References 20 publications

Point-contact spectroscopy of the antiferromagnetic superconductorHoNi2B2Cin the normal and superconducting state

Point-contact spectroscopy of the antiferromagnetic superconductorHoNi2B2Cin the normal and superconducting state

Phonons and electron-phonon coupling in YNi2B2C

Andreev-Reflection and Point-Contact Spectroscopy of Superconducting Rare Earth Transition Metal Borocarbides

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