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arXiv · 2504.11863

Understanding the evolution of the magnetic ground state in Ba$_4$NaRu$_3$O$_{12}$

Shruti Chakravarty·Pascal Manuel·Antonio Cervellino·Sunil Nair
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Abstract

We report a comprehensive investigation of the quadruple perovskite Ba$_4$NaRu$_3$O$_{12}$, in which we discover a robust spin-lattice coupled ground state characterized by a long-range antiferromagnetic ordering at $T_N \sim$ 257 K. The system's unique structural motif of three symmetrically distinct magnetic ions, including Ru dimers separated by non-magnetic layers, is intimately correlated with its magnetic behavior, as evidenced by temperature-dependent diffraction measurements and specific heat data. The powder neutron diffraction patterns at 13 K showed that the spins within the dimers are antiparallel, leading to a net zero moment contribution and a staggered arrangement of the triangular layers formed by the Ru moments within the corner-shared octahedra along the $c$-axis. The low-temperature specific heat revealed an extra boson peak contribution from optical modes with a maximum vibrational energy of $\sim$55cm$^{-1}$. The charge transport exhibited variable-range hopping (VRH) behaviour below $T_N$, with a stronger energy-dependence than expected from the Efros-Shklovskii model, suggesting the presence of multiparticle correlation effects.

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Shruti Chakravarty, Pascal Manuel, Antonio Cervellino, Sunil Nair. 2025-04-16. Understanding the evolution of the magnetic ground state in Ba$_4$NaRu$_3$O$_{12}$. https://arxiv.org/abs/2504.11863

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