Spectroscopic evidence of nematic fluctuations in LiFeAs

Abstract

The role of nematic fluctuations in the pairing mechanism of iron-based superconductors is frequently debated. Here we present a novel method to reveal such fluctuations by identifying energy and momentum of the corresponding nematic boson through the detection of a boson-assisted resonant amplification of Friedel oscillations. Using Fourier-transform scanning tunneling spectroscopy, we observe for the unconventional superconductor LiFeAs strong signatures of bosonic states at momentum $q\sim 0$ and energy $\Omega \approx 8$~meV. We show that these bosonic states survive in the normal conducting state, and, moreover, that they are in perfect agreement with well-known strong above-gap anomalies in the tunneling spectra. Attributing these small-$q$ boson modes to nematic fluctuations we provide the first spectroscopic approach to the nematic boson in an unconventional superconductor.

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Cited by in corpus (5)

• Two distinct superconducting states controlled by orientation of local wrinkles in LiFeAs
• Electron and Superconducting Properties of the AFeAs (A= Li, Na) Family Alkali-Metal Pnictides: Current Stage of the Research (mini-review)
• Orbital selectivity of layer resolved tunneling on iron superconductor Ba0.6K0.4Fe2As2
• Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit
• Absence of nematic instability in LiFeAs