We use polarization-resolved electronic Raman spectroscopy to study charge dynamics in non-magnetic FeSe1−xSx superconductor. We observe two features of the XY quadrupole symmetry: a low-energy quasi-elastic peak (QEP) and an electronic continuum. The QEP exhibits critical enhancement upon cooling towards the structural transition at TS(x). Below TS(x), the QEP diminishes gradually, and a gap with temperature evolution reminiscent of a mean-field order parameter opens in the continuum. The intensity of the QEP develops with increasing sulfur doping x and maximizes at x≈ 0.15, while the gap magnitude decreases with the suppression of TS(x). We interpret the development of the gap in the quadrupole scattering channel as the formation of a stripe quadrupole order: a wave of quadrupole moment without charge or spin modulation.
@article{arxiv.1710.09892,
title = {Quadrupolar charge dynamics in the nonmagnetic FeSe$_{1-x}$S$_x$ superconductors},
author = {W. -L. Zhang and S. -F. Wu and S. Kasahara and T. Shibauchi and Y. Matsuda and G. Blumberg},
journal= {arXiv preprint arXiv:1710.09892},
year = {2021}
}
Comments
This is a preprint of an article published in the Proceedings of the National Academy of Sciences (PNAS). The final authenticated version is available online at: https://doi.org/10.1073/pnas.2020585118