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arXiv · 2504.06113

Interplay between trimer structure and magnetic ground state in Ba5Ru3O12 probed by Neutron and muSR techniques

E. Kushwaha·S. Ghosh·J. Sannigrahi·G. Roy·M. Kumar·S. Cottrell·M. B. Stone·Y. Fang·D. T. Adroja·X. Ke·T. Basu
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Abstract

We report a detailed inelastic neutron scattering (INS) and muon spin relaxation (muSR) investigation of a trimer Ruthenate Ba5Ru3O12 system, which undergoes long-range antiferromagnetic ordering at TN = 60 K. The INS reveals two distinct spin wave excitations below TN: one at 5.6 meV and the other at 10-15 meV. By accompanying the INS spectra based on a linear spin wave theory using SpinW software and machine learning force fields (MLFFs), we show that Ba5Ru3O12 exhibits spin frustration due to competing exchange interactions between neighboring and next-neighboring Ru-moments, exchange anisotropy, and strong spin-orbit coupling, which yields a non-collinear spin structure, in contrast to other ruthenate trimers in this series. Interestingly, these magnetic excitations do not completely vanish even at high temperatures above TN, evidencing short-range magnetic correlations in this trimer system. This is further supported by muSR spectroscopy, which exhibits a gradual drop in the initial asymmetry around the magnetic phase transition and is further verified through maximum entropy analysis. The results of muSR spectroscopy indicate a dynamic nature of magnetic order, attributed to local magnetic anisotropy within the trimer as a result of local structural distortion and different hybridization, consistent with canted spin-structure. We predict the ground state of Ru3O12-isolated trimer through theoretical calculations, which agree with the experimentally observed spin excitation

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E. Kushwaha, S. Ghosh, J. Sannigrahi, G. Roy, M. Kumar, S. Cottrell, M. B. Stone, Y. Fang, D. T. Adroja, X. Ke, T. Basu. 2025-04-08. Interplay between trimer structure and magnetic ground state in Ba5Ru3O12 probed by Neutron and muSR techniques. https://doi.org/10.1103/c5s4-4hxw

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