Magnetic properties of a staggered S=1 chain with an alternating single-ion anisotropy direction

Vaidya, S.; Curley, S. P. M.; Manuel, P.; Stewart, J. Ross; Le, M. Duc; Balz, C.; Shiroka, T.; Blundell, S. J.; Wheeler, K. A.; Calderon-Lin, I.; Manson, Z. E.; Manson, J. L.; Singleton, J.; Lancaster, T.; Johnson, R. D.; Goddard, P. A.

Abstract

Materials composed of spin-1 antiferromagnetic (AFM) chains are known to adopt complex ground states that are sensitive to the single-ion-anisotropy (SIA) energy (𝐷), and intrachain (𝐽0) and interchain (𝐽′1,2) exchange energy scales. While theoretical and experimental studies have extended this model to include various other energy scales, the effect of the lack of a common SIA axis is not well explored. Here we investigate the magnetic properties of Ni⁡(pyrimidine)⁢(H2⁡O)2⁢(NO3)2, a chain compound where the tilting of Ni octahedra leads to a twofold alternation of the easy-axis directions along the chain. Muon-spin relaxation measurements indicate a transition to long-range order at 𝑇N=2.3K and the magnetic structure is initially determined to be antiferromagnetic and collinear using elastic neutron diffraction experiments. Inelastic neutron scattering measurements were used to find 𝐽0=5.107⁢(7)⁢K, 𝐷=2.79⁢(1)⁢K,𝐽′1=0.00⁢(5)⁢K, 𝐽′2=0.18⁢(3)⁢K, and a rhombic anisotropy energy 𝐸=0.19⁢(9)⁢K. Mean-field modeling reveals that the ground state structure hosts spin canting of 𝜙≈6.5∘, which is not detectable above the noise floor of the elastic neutron diffraction data. Monte Carlo simulation of the powder-averaged magnetization, 𝑀⁡(𝐻), is then used to confirm these Hamiltonian parameters, while single-crystal 𝑀⁡(𝐻) simulations provide insight into features observed in the data.

Citation

Vaidya, S., Curley, S. P. M., Manuel, P., Stewart, J. R., Le, M. D., Balz, C., Shiroka, T., Blundell, S. J., Wheeler, K. A., Calderon-Lin, I., Manson, Z. E., Manson, J. L., Singleton, J., Lancaster, T., Johnson, R. D., & Goddard, P. A. (2025). Magnetic properties of a staggered S=1 chain with an alternating single-ion anisotropy direction. Physical Review B, 111, Article 014421. https://doi.org/10.1103/physrevb.111.014421

• Journal Article Type: Article
• Acceptance Date: Dec 4, 2024
• Online Publication Date: Jan 17, 2025
• Publication Date: Jan 17, 2025
• Deposit Date: Jan 24, 2025
• Publicly Available Date: Jan 27, 2025
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 111
• Article Number: 014421
• DOI: https://doi.org/10.1103/physrevb.111.014421
• Public URL: https://durham-repository.worktribe.com/output/3349609