Neutron scattering and muon-spin spectroscopy studies of the magnetic triangular-lattice compounds A&lt;sub&gt;2&lt;/sub&gt;La&lt;sub&gt;2&lt;/sub&gt;NiW&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; (&lt;em&gt;A&lt;/em&gt; = Sr, Ba)

Yu, B.C.; Yang, J.Y.; Gawryluk, D.J.; Xu, Y.; Zhan, Q.F.; Shiroka, T.; Shang, T.

doi:10.1103/PhysRevMaterials.7.074403

Neutron scattering and muon-spin spectroscopy studies of the magnetic triangular-lattice compounds A₂La₂NiW₂O₁₂ (A = Sr, Ba)

Yu BC, Yang JY, Gawryluk DJ, Xu Y, Zhan QF, Shiroka T & Shang T

Citation

Yu, B. C., Yang, J. Y., Gawryluk, D. J., Xu, Y., Zhan, Q. F., Shiroka, T., & Shang, T. (2023). Neutron scattering and muon-spin spectroscopy studies of the magnetic triangular-lattice compounds A₂La₂NiW₂O₁₂ (A = Sr, Ba). Physical Review Materials, 7(7), 074403 (9 pp.). https://doi.org/10.1103/PhysRevMaterials.7.074403

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:54262

We report on the geometrically frustrated two-dimensional triangular-lattice magnets A₂La₂NiW₂O₁₂ (A = Sr,Ba) studied mostly by means of neutron powder diffraction (NPD) and muon-spin rotation and relaxation (μSR) techniques. The chemical pressure induced by the Ba-for-Sr substitution suppresses the ferromagnetic (FM) transition from 6.3 K in the Ba compound to 4.8 K in the Sr compound. We find that the R¯3 space group reproduces the NPD patterns better than the previously reported R¯3m space group. Both compounds adopt the same magnetic structure with a propagation vector k = (0,0,0), in which the Ni²⁺ magnetic moments are aligned ferromagnetically along the c axis. The zero-field μSR results reveal two distinct internal fields (0.31 and 0.10 T), caused by the long-range FM order. The small transverse muon-spin relaxation rates reflect the homogeneous internal field distribution in the ordered phase and, thus, further support the simple FM arrangement of the Ni²⁺ moments. The small longitudinal muon-spin relaxation rates, in both the ferromagnetic and paramagnetic states of A₂La₂NiW₂O₁₂, indicate that spin fluctuations are rather weak. Our results demonstrate that chemical pressure indeed changes the superexchange interactions in A₂La₂NiW₂O₁₂ compounds, with the FM interactions being dominant.