Field-induced incipient spin-density phase stabilized inside the nematic phase of FeSe1−xSx
Abstract
Spin-density wave (SDW) order and superconductivity frequently compete and coexist in unconventional superconductors, where spin fluctuations often mediate superconducting pairing. In iron-chalcogenide superconductors, FeSe1−xSx, SDW order has only been detected under applied pressure, while both spin and nematic fluctuations are involved in determining their rich superconducting phase diagrams. Here, we report evidence for an incipient SDW phase, within the nematic state of FeSe1−xSx, revealed in magnetic fields up to 68~T. Once superconductivity is quenched, we observe sharp upturns in longitudinal resistivity accompanied by anomalies in tunnel diode oscillator frequency response and torque anisotropy, consistent with a field-induced electronic order. Dominant low-frequency quantum oscillations reveal a small reconstructed Fermi surface, consistent with a field-induced SDW order. Direct experimental comparisons with a pressure-tuned nematic, analogue, FeSe0.96S0.04, demonstrate that SDW phases are stabilized within the nematic phase of FeSe1−xSx via both chemical substitution and applied pressure. These findings reveal that by weakening nematicity, the SDW orders are stabilised, which promotes the dominant superconducting pairing mechanism in iron chalcogenides.
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BibTeX
@misc{paulescu2026fieldinduced,
title = {{Field-induced incipient spin-density phase stabilized inside the nematic phase of FeSe$_1-x$S$_x$}},
author = {I. Paulescu and R. M. Abedin and J. S. Pearce and W. H. Fong and Z. Zajicek and A. Morfoot and W. Knafo and O. Squire and D. Graf and A. A. Haghighirad and A. I. Coldea},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28446},
eprint = {2609.28446},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28446},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Field-induced incipient spin-density phase stabilized inside the nematic phase of FeSe_1−xS_x
AU - I. Paulescu
AU - R. M. Abedin
AU - J. S. Pearce
AU - W. H. Fong
AU - Z. Zajicek
AU - A. Morfoot
AU - W. Knafo
AU - O. Squire
AU - D. Graf
AU - A. A. Haghighirad
AU - A. I. Coldea
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28446
UR - https://arxiv.org/abs/2609.28446
AB - Spin-density wave (SDW) order and superconductivity frequently compete and coexist in unconventional superconductors, where spin fluctuations often mediate superconducting pairing. In iron-chalcogenide superconductors, FeSe_1−xS_x, SDW order has only been detected under applied pressure, while both spin and nematic fluctuations are involved in determining their rich superconducting phase diagrams. Here, we report evidence for an incipient SDW phase, within the nematic state of FeSe_1−xS_x, revealed in magnetic fields up to 68~T. Once superconductivity is quenched, we observe sharp upturns in longitudinal resistivity accompanied by anomalies in tunnel diode oscillator frequency response and torque anisotropy, consistent with a field-induced electronic order. Dominant low-frequency quantum oscillations reveal a small reconstructed Fermi surface, consistent with a field-induced SDW order. Direct experimental comparisons with a pressure-tuned nematic, analogue, FeSe_0.96S_0.04, demonstrate that SDW phases are stabilized within the nematic phase of FeSe_1−xS_x via both chemical substitution and applied pressure. These findings reveal that by weakening nematicity, the SDW orders are stabilised, which promotes the dominant superconducting pairing mechanism in iron chalcogenides.
ER -