<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Sm</mml:mi><mml:msub><mml:mi mathvariant="normal">I</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>:</mml:mo><mml:mspace width="0.16em"/><mml:mn>4</mml:mn><mml:msup><mml:mi>f</mml:mi><mml:mn>5</mml:mn></mml:msup></mml:mrow></mml:math> honeycomb magnet with spin-orbital entangled <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Γ</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:math> Kramers doublet
Hajime Ishikawa, Ryosuke Kurihara, Takeshi Yajima, Daisuke Nishio‐Hamane, Yusei Shimizu, Toshiro Sakakibara, Akira Matsuo, Koichi Kindo
Abstract
We report magnetic properties of a $4f$ honeycomb iodide $\mathrm{Sm}{\mathrm{I}}_{3}$ made up of edge-shared network of $\mathrm{Sm}{\mathrm{I}}_{6}$ octahedra. High temperature magnetic susceptibility indicates a ${\mathrm{\ensuremath{\Gamma}}}_{7}$ Kramers doublet ground state of ${\mathrm{Sm}}^{3+}(4{f}^{5})$ ions stabilized by the spin-orbit coupling and octahedral crystal electric field, which interact with a Sm-I-Sm bond angle of nearly ${90}^{\ensuremath{\circ}}$. Magnetization measurements down to 0.1 K detected antiferromagnetic correlations and an anomaly in the magnetization curve before saturation without a sign of long-range order. Relevance between $\mathrm{Sm}{\mathrm{I}}_{3}$ and the antiferromagnetic Kitaev material proposed in the $4f\text{\ensuremath{-}}\mathrm{electron}$ system is discussed.