Superconductivity and phonon self-energy effects in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$

S. -F. Wu; A. Almoalem; I. Feldman; A. Lee; A. Kanigel; G. Blumberg

doi:10.1103/physrevresearch.2.013373

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arXiv · 1911.07270

Superconductivity and phonon self-energy effects in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$

S. -F. Wu·A. Almoalem·I. Feldman·A. Lee·A. Kanigel·G. Blumberg

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Abstract

We study Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ multi-band superconductor with $T_c=14$K by polarization-resolved Raman spectroscopy. Deep in the superconducting state, we detect pair-breaking excitation at 45cm$^{-1}$ ($2\Delta=5.6$meV) in the $XY$($B_{2g}$) scattering geometry, consistent with twice of the superconducting gap energy (3 meV) revealed by ARPES on the hole-like Fermi pocket with $d_{xz}/d_{yz}$ character. We analyze the superconductivity induced phonon self-energy effects for the $B_{1g}$(Fe) phonon and estimate the electron-phonon coupling constant $\lambda^\Gamma \approx 0.026$, which is insufficient to explain superconductivity with $T_c=14$K.

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S. -F. Wu, A. Almoalem, I. Feldman, A. Lee, A. Kanigel, G. Blumberg. 2019-11-17. Superconductivity and phonon self-energy effects in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$. https://doi.org/10.1103/physrevresearch.2.013373

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