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arXiv · 1412.5818

Electron-boson spectral density of LiFeAs obtained from optical data

J. Hwang·J. P. Carbotte·B. H. Min·Y. S. Kwon·T. Timusk
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Abstract

We analyze existing optical data in the superconducting state of LiFeAs at $T =$ 4 K, to recover its electron-boson spectral density. A maximum entropy technique is employed to extract the spectral density $I^2χ(ω)$ from the optical scattering rate. Care is taken to properly account for elastic impurity scattering which can importantly affect the optics in an $s$-wave superconductor, but does not eliminate the boson structure. We find a robust peak in $I^2χ(ω)$ centered about $Ω_R \cong$ 8.0 meV or 5.3 $k_B T_c$ (with $T_c =$ 17.6 K). Its position in energy agrees well with a similar structure seen in scanning tunneling spectroscopy (STS). There is also a peak in the inelastic neutron scattering (INS) data at this same energy. This peak is found to persist in the normal state at $T =$ 23 K. There is evidence that the superconducting gap is anisotropic as was also found in low temperature angular resolved photoemission (ARPES) data.

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J. Hwang, J. P. Carbotte, B. H. Min, Y. S. Kwon, T. Timusk. 2014-12-18. Electron-boson spectral density of LiFeAs obtained from optical data. https://doi.org/10.1088/0953-8984%2F27%2F5%2F055701

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