Raman Study of Cooper Pairing Instabilities in (Li${}_{1-x}$Fe${}_x$)OHFeSe

Abstract

We studied the electronic Raman spectra of (Li${}_{1-x}$Fe${}_x$)OHFeSe as a function of light polarization and temperature. In the B${}_{1g}$ spectra alone we observe the redistribution of spectral weight expected for a superconductor and two well-resolved peaks below T${}_c$. The nearly resolution-limited peak at 110 cm${}^{-1}$ (13.6 meV) is identified as a collective mode. The peak at 190 cm${}^{-1}$ (23.6 meV) is presumably another collective mode since the line is symmetric and its energy is significantly below the gap energy observed by single-particle spectroscopies. Given the experimental band structure of (Li${}_{1-x}$Fe${}_x$)OHFeSe, the most plausible explanations include conventional spin-fluctuation pairing between the electron bands and the incipient hole band and pairing between the hybridized electron bands. The absence of gap features in A${}_{1g}$ and B${}_{2g}$ symmetry favors the second case. Thus, in spite of various differences between the pnictides and chalcogenides, this Letter demonstrates the proximity of pairing states and the importance of band structure effects in the Fe-based compounds.

arXiv comment9 pages, 12 figures

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Cited by in corpus (7)

• Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors
• A disorder-sensitive emergent vortex phase identified in high-Tc superconductor (Li,Fe)OHFeSe
• Many-body physics-induced selection rules: application to Raman spectroscopy
• The role of orbital nesting in the superconductivity of Iron-based Superconductors
• Signatures of Bardasis-Schrieffer mode excitation in Third-Harmonic generated currents
• Raman response of collective modes in multicomponent superconductors
• Extracting intrinsic superconducting properties in intercalated layered superconductors using an extended 2D Tinkham model