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arXiv · 2404.06923

$J_{\rm{eff}}$ = 1/2 Hyperoctagon Lattice in Cobalt Oxalate Metal-Organic-Framework

Hajime Ishikawa·Shusaku Imajo·Hikaru Takeda·Masafumi Kakegawa·Minoru Yamashita·Jun-ichi Yamaura·Koichi Kindo
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Abstract

We report the magnetic properties of a cobalt oxalate metal-organic-framework featuring the hyperoctagon lattice. Our thermodynamic measurements reveal the $J_{\rm{eff}}$ = 1/2 state of the high-spin Co$^{2+}$ (3$\textit{d}^{7}$) ion and the two successive magnetic transitions at zero field with two-stage entropy release. $^{13}$C-NMR measurements reveal the absence of an internal magnetic field in the intermediate temperature phase. Multiple field-induced phases are observed before full saturation at around 40 T. We argue the unique cobalt oxalate network gives rise to the Kitaev interaction and/or a bond frustration effect, providing an unconventional platform for frustrated magnetism on the hyperoctagon lattice.

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Hajime Ishikawa, Shusaku Imajo, Hikaru Takeda, Masafumi Kakegawa, Minoru Yamashita, Jun-ichi Yamaura, Koichi Kindo. 2024-04-10. $J_{\rm{eff}}$ = 1/2 Hyperoctagon Lattice in Cobalt Oxalate Metal-Organic-Framework. https://doi.org/10.1103/physrevlett.132.156702

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