Pressure Effect on the Einstein-Like Phonon Mode in Superconducting \(\hbox {YB}_{6}\)

Abstract

\(\hbox {YB}_{6}\) is known as a conventional type-II BCS superconductor in which the strong coupling superconductivity with \(2\Delta /k_{B}T_{c}\approx 4.1\) is mediated by the Einstein-like phonon mode of Y atoms located at \(\hbar \omega _{E}\approx 8\,\hbox {meV}\). We have investigated the pressure effect on \(\omega _{E}\) by Raman scattering up to 14 GPa. The received linear pressure increase in this mode \(d\omega _{E}/dp\approx \) 0.21 meV/GPa yields an isothermal Grüneisen coefficient \(\gamma _{T}= -\partial \hbox {ln}\omega _{E}/\partial \hbox {ln} V = 3.85\). Moreover, the pressure effect on the electron–phonon interaction \(\lambda \) calculated from the McMillan–Allen–Dynes expression for the superconducting transition temperature was determined to be \(\partial \hbox {ln}{\lambda }/\partial \hbox {ln}V \cong 7.2\).

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Acknowledgements

This work was supported by Projects VEGA 2/0032/16, APVV-14-0605, EU ERDF-ITMS 26110230097 and by CFNT MVEP project of the Slovak Academy of Sciences. Sponsorship of US Steel Kosice is appreciated too.

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Correspondence to S. Gabáni.

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Orendáč, M., Gabáni, S., Gažo, E. et al. Pressure Effect on the Einstein-Like Phonon Mode in Superconducting \(\hbox {YB}_{6}\) . J Low Temp Phys 187, 553–558 (2017). https://doi.org/10.1007/s10909-016-1728-0

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Keywords

  • Superconductivity
  • High pressures
  • Raman scattering