Structure, Magnetism, and Crystalline Electric Field Effects in Ce_3​TiBi₅​ and Ce₃​ZrBi₅​

We present a comprehensive study of structural and magnetic properties in the intermetallic compounds Ce_3​TiBi₅​ and Ce₃​ZrBi₅ through complementary powder diffraction, single-crystal neutron diffraction, and inelastic neutron scattering experiments. Rietveld refinement of high-resolution powder neutron diffraction data reveals lattice constants and atomic positions consistent with the P63/mcm space group across both compounds. Powder and single-crystal neutron diffraction measurements confirm magnetic ordering with very similar propagation vectors for Ce_3​TiBi₅​ and Ce₃​ZrBi₅. Detailed analysis reveals incommensurate magnetic order along (H 0 L±δ) wave vectors, with a critical temperature TN≈5 K for Ce3TiBi5​, and a critical exponent β of 0.34(3), consistent with 3D Heisenberg behavior.Inelastic neutron scattering measurements at varying temperatures demonstrate crystalline electric field (CEF) excitations at ∼12, ∼27, and ∼300 meV, which we assign to transitions based upon the J=5/2 manifold and to the J=7/2 manifold, respectively. For both compounds, the CEF modes exhibit minimal temperature-dependent energy shifts for temperatures between 5 and 150 K suggesting robust magnetic interactions within this range. Our preliminary low-energy investigation of the spectrum indicates potential collective magnetic excitations.