Direct observation of superconducting gap in YB6 by ultrahigh-resolution photoemission spectroscopy

Souma, S.; Komoda, Hirotaka; Iida, Yoshihiro; Sato, Takafumi; Takahashi, Takashi; Kunii, S.

doi:10.1016/j.elspec.2005.01.125

Cited by 11 publications

(8 citation statements)

References 11 publications

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“…Also an EPI peak at 11 meV was observed with the gap energy subtracted. The photo-emission spectroscopy results of Souma et al [11] indicate similar conclusions. Schneider et al [12] prepared the tunneling sandwich on YB 6 film naturally oxidized with In top electrode and obtained 2∆/k B T c ≈ 4, the intense EPI peak at 8 meV in discrepancy with Kunii and λ ≈ 0.9.…”

Section: Introductionsupporting

confidence: 77%

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Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Szabó

Girovský

Kačmarčı́k

et al. 2013

Supercond. Sci. Technol.

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Lortz et al. [Phys. Rev. B 73, 024512 (2006)] have utilized specific heat and resistivity measurements as "thermal spectroscopies" to deconvolve the spectrum of the electron-phonon interaction in YB6 assuming a major role of the low frequency phonon mode in mediating superconductivity. Here, we present direct point-contact spectroscopy studies of the superconducting interaction in this system. As a result the normalized superconducting gap reveals a strong coupling with 2∆/kBTc = 4 and moreover the spectra contain nonlinearities typical of the electron-phonon interaction at energies around 8 meV. The in-magnetic-field measurements evidence that the phonon features found in the second derivative of the current-voltage characteristics are due to the energy dependence of the superconducting energy gap as their energy position shrinks equally as the gap is closing. This is a direct proof that the superconducting coupling in the system is due to the low energy Einstein-like phonon mode associated with the yttrium ion vibrations in a perfect agreement with determinations from bulk measurements.

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Section: Introductionsupporting

confidence: 77%

“…In contrast to the reports in Refs. [10,11] no structure was observed at ∼ 11 meV in any of the several junctions revealing detectable non-linearities in the d 2 V /dI 2 (V ) spectra on our Pt-YB 6 hetero-contacts. Yet no structures apart of the smoothly increasing background was observed at higher voltages above 30 mV.…”

mentioning

confidence: 99%

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Szabó

Girovský

Kačmarčı́k

et al. 2013

Supercond. Sci. Technol.

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“…In the case of YB 6 , p 3 at 154 cm −1 corresponds to twice of 10meV (80 cm −1 ) phonon reported by [1] and [2]. Therefore, p 3 in Fig.…”

Section: Resultsmentioning

confidence: 91%

“…The gap parameter was determined by an electron tunneling experiment as 2∆ 0 /k B T c =3.8 1) and was also verified by an ultrahigh-resolution photoemission spectroscopy. 2) Both reports concluded that YB 6 is categorized into a strong coupling BCS superconductor mediated by phonon with the energy of 10meV. This phonon mode seems to be a local vibration of Y with large amplitude based on our previous Raman study.…”

Section: Introductionmentioning

confidence: 99%

Raman Scattering of YB₆

et al. 2011

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Temperature and polarization dependencies of Raman scattering spectra of YB 6 have been measured in the temperature region from room temperature to 2.4K. All Raman active modes have been observed and well assigned by the polarization dependence. The observation of the doublet structure of T 2g and E g peaks suggests the crystallographic symmetry of P4/mmm for YB 6 , not Pm3m from group theoretical consideration. In the lower energy region than 200cm −1 , the peaks due to the Y vibration have been observed. Within the present experimental accuracy, any anomalies of phonon spectra have not been observed at the superconducting transition temperature.

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“…The isostructural forms of MB 6 are superconductors (e.g. M = Y, Th) [1,2], metallic conductors (e.g. M = La, Gd, Dy) [3,4] and semi-conductors (e.g.…”

Section: Introductionmentioning

confidence: 99%

Metal Hexaborides with Sc, Ti or Mn

Alarco¹,

Talbot²

2013

MNSMS

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Comparison of well-determined single crystal data for stoichiometric, or near-stoichiometric, metal hexaborides confirms previously identified lattice parameter trends using powder diffraction. Trends for both divalent and trivalent forms suggest that potential new forms for synthesis include Sc and Mn hexaborides. Density Functional Theory (DFT) calculations for KB 6 , CaB 6 , YB 6 , LaB 6 , boron octahedral clusters and Sc and Mn forms show that the shapes of bonding orbitals are defined by the boron framework. Inclusion of metal into the boron framework induces a reduction in energy ranging from 1 eV to 6 eV increasing with ionic charge. For metals with d 1 character, such a shift in energy brings a doubly degenerate band section along with the G-M reciprocal space direction within the conduction bands tangential to the Fermi surface. ScB 6 band structure and density of states calculations show directions and gap characteristics similar to those of YB 6 and LaB 6 . These calculations for ScB 6 suggest that it may be possible to realize superconductivity in this compound if synthesized.

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Direct observation of superconducting gap in YB6 by ultrahigh-resolution photoemission spectroscopy

Cited by 11 publications

References 11 publications

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Raman Scattering of YB₆

Metal Hexaborides with Sc, Ti or Mn

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Direct observation of superconducting gap in YB6 by ultrahigh-resolution photoemission spectroscopy

Cited by 11 publications

References 11 publications

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB6

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB6

Raman Scattering of YB6

Metal Hexaborides with Sc, Ti or Mn

Contact Info

Product

Resources

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Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB₆

Raman Scattering of YB₆