Entanglement of spin and orbital degrees of freedom, via relativistic spin-orbit coupling, in 4d transition metal oxides can give rise to a variety of novel quantum phases. A previous study of mixed 3d-4d quasi-1D spin-chain oxide Sr3NiRhO6 using the magnetization measurements by Mohapatra et al. [Phys. Rev. B 75, 214422 (2007)] revealed a partially disordered antiferromagnetic (PDA) structure below 50 K [Mohapatra et al, Phys. Rev. B 75, 214422 (2007)]. We here report the magnetic ground state and spin-wave excitations in Sr3NiRhO6, using muon spin rotation and relaxation (μSR), and neutron (elastic and inelastic) scattering techniques. Our neutron diffraction study reveals that in the magnetic structure of Sr3NiRhO6, Rh4+ and Ni2+ spins are aligned ferromagnetically in a spin-chain, with moments along the crystallographic c-axis. However, spin-chains are coupled antiferromanetically in the ab-plane. μSR reveals the presence of oscillations in the asymmetry-time spectra below 50 K, supporting the long-range magnetically ordered ground state. Our inelastic neutron scattering study reveals gapped quasi-1D magnetic excitations with a large ratio of gap to exchange interaction. The observed spin-wave spectrum could be well fitted with a ferromagnetic isotropic exchange model (with J=3.7 meV) and single ion anisotropy (D=10 meV) on the Ni2+ site. The magnetic excitations survive up to 85 K, well above the magnetic ordering temperature of ∼50 K, also indicating a quasi-1D nature of the magnetic interactions in Sr3NiRhO6.
@article{arxiv.2411.12088,
title = {Magnetic ground state and excitations in mixed 3$d$-4$d$ quasi-1D spin-chain oxide Sr$_3$NiRhO$_6$},
author = {A. Jain and D. T. Adroja and S. Rayaprol and A. D. Hillier and W. Kockelmann and S. M. Yusuf and E. V. Sampathkumaran},
journal= {arXiv preprint arXiv:2411.12088},
year = {2025}
}