High-energy spin waves in the spin-1 square-lattice antiferromagnet La2NiO4

Journal article

Inelastic neutron scattering is used to study the magnetic excitations of the S=1 square-lattice antiferromagnet La₂NiO₄. We find that the spin waves cannot be described by a simple classical (harmonic) Heisenberg model with only nearest-neighbor interactions. The spin-wave dispersion measured along the antiferromagnetic Brillouin-zone boundary shows a minimum energy at the (1/2,0) position as is observed in some S=1/2 square-lattice antiferromagnets. Thus, our results suggest that the quantum dispersion renormalization effects or longer-range exchange interactions observed in cuprates and other S =1/2 square-lattice antiferromagnets are also present in La₂NiO₄. We also find that the overall intensity of the spin-wave excitations is suppressed relative to linear spin-wave theory, indicating that covalency is important. Two-magnon scattering is also observed.

Authors: Petsch, AN; Headings, NS; Prabhakaran, D; Kolesnikov, AI; Frost, CD

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Research
• Volume: 5
• Issue: 3
• Article number: 033113
• Publication date: 2023-08-18
• Acceptance date: 2023-07-13
• DOI: 10.1103/PhysRevResearch.5.033113
• EISSN: 2643-1564
• Language: English
• Keywords: quantum physics; classical physics; FFR; physical sciences