Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 3: Complex Magnetic Oxides
MA 3.12: Talk
Monday, March 9, 2026, 12:30–12:45, POT/0112
Long-range spin density wave order in bilayer nickelates revealed by neutron diffraction — •Igor Plokhikh — TU Dortmund University, Department of Physics, 44227 Dortmund, Germany — Research Center Future Energy Materials and Systems, 44227 Dortmund, Germany
The observation of pressure-induced superconductivity in Ruddlesden Popper nickelates has triggered renewed interest in their magnetic ground states as potential precursors to unconventional superconductivity [1]. Using high-intensity neutron powder diffraction (NPD) complemented by muon-spin rotation/relaxation (µSR), we directly resolve long-range spin-density-wave (SDW) order in bilayer La3Ni2O7 and La2PrNi2O7 below 150 K [2].
Magnetic Bragg reflections appear at propagation vectors q1 = (0,12,0) for both compounds and an additional vector q2 = (12,12,0) exclusively in undoped La3Ni2O7. Representation analysis reveals amplitude-modulated SDW structures composed of alternating low- (≈ 0.05 µB) and high-moment (≈ 0.7 µB) Ni sites forming antiferromagnetically stacked bilayers along the c-axis. The coexistence of two distinct stacking polymorphs corresponding to q1 and q2 reflects quasi-two-dimensional magnetic order intrinsic to this system.
These findings provide the first direct neutron evidence for SDW order in bilayer nickelates and offer crucial insights into their ground state.
[1] Wang et al., Chinese Phys. Lett. 41, 077402 (2024).
[2] Plokhikh et al., arXiv:2503.05287(2025).
Keywords: Ruddlesden–Popper nickelate superconductors; Spin density wave; Neutron diffraction