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arXiv · 2308.11172

Magnetic ordering in the $J_{\rm eff}$ = 0 Nickelate NiRh$_2$O$_4$ prepared via a solid-state metathesis

Yuya Haraguchi·Daisuke Nishio-Hamane·Hiroko Aruga Katori
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Abstract

In spinel-type nickelate NiRh$_2$O$_4$, magnetic ordering is observed upon the sample synthesized via kinetically controlled low-temperature solid-state metathesis, as opposed to previously-reported samples obtained through conventional solid-state reaction. Our findings are based on a combination of bulk susceptibility and specific heat measurements that disclose a N$\'e$el transition temperature of $T_N$ = 45 K in this material, which might feature spin-orbit entanglement in the tetragonally-coordinated $d^8$ Mott insulators. The emergence of magnetic ordering upon alteration of the synthesis route indicates that the suppression of magnetic ordering in the previous sample was rooted in the cation-mixing assisted by the entropy gain that results from high-temperature reactions. Furthermore, the $J_{\rm eff}$ = 0 physics, instead of solely the spin-only $S = 1$, describes the observed enhancement of effective magnetic moment well. Overseeing all observations and speculations, we propose that the possible mechanism responsible for the emergent magnetic orderings in NiRh$_2$O$_4$ is the condensation of $J_{\rm eff}$ = 0 exciton, driven by the interplay of the tetragonal crystal field and superexchange interactions.

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Yuya Haraguchi, Daisuke Nishio-Hamane, Hiroko Aruga Katori. 2023-08-22. Magnetic ordering in the $J_{\rm eff}$ = 0 Nickelate NiRh$_2$O$_4$ prepared via a solid-state metathesis. https://doi.org/10.1103/physrevmaterials.7.084413

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