- By:
- Anderson, Zachary; Tang, Y; Chan, M; Dorow, C; Yu, G; Abernathy, Douglas L; Christianson, Andrew D; Mangin-Thro, L; Steffens, P; Sterling, T; Reznik, Dmitry; Bounoua, D; Sidis, Y.; Bourges, Philippe; Greven, M.
- Journal Name:
- npj Quantum Materials
- Page Number:
- 93
- Volume:
- 10
- Issue Number:
- 1
- Publication Date:
- August 22, 2025
- View DOI Listing:
- https://doi.org/10.1038/s41535-025-00804-0
Abstract
It is a distinct possibility that spin fluctuations are the pairing interactions in numerous unconventional superconductors. In the high-transition-temperature (high-Tc) cuprates, superconductivity emerges upon doping antiferromagnetic Mott insulators, and spin fluctuations might furthermore drive unusual pseudogap phenomena. Here we use magnetic neutron scattering to study the highly underdoped cuprate HgBa2CuO4+δ (hole concentration p ≈ 0.064). In contrast to prior results for other underdoped cuprates, we find no evidence of incommensurate magnetic order associated with spin-density-wave or stripe correlations. Instead, the antiferromagnetic response in both the superconducting and pseudogap states is gapped below ΔAF ≈ 6 meV, commensurate over a wide energy range, and disperses above about 55 meV. Given the pristine nature of HgBa2CuO4+δ, which exhibits high structural symmetry and minimal point disorder effects, this behavior likely signifies the unmasked response of the underlying CuO2 planes near the Mott-insulating state. These results serve as a benchmark for a refined theoretical understanding of the cuprates.
