Spin-phonon-charge coupling in the two-dimensional honeycomb lattice compound Ni2Te3O8

A two-dimensional honeycomb-structured magnet ${\mathrm{Ni}}_{2}{\mathrm{Te}}_{3}{\mathrm{O}}_{8}$ was synthesized, characterized, and comprehensively investigated for its intriguing physical properties. DC magnetization, specific heat, and neutron diffraction revealed a long-range commensurate antiferromagnetic ordering at ${T}_{\mathrm{N}}\ensuremath{\sim}35\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with a propagation vector $\mathbf{k}=(100)$. The magnetic sublattice comprises stacking distorted honeycomb layers along the $a$ axis. The ${\mathrm{Ni}}^{2+}$ spins on the honeycomb lattice are essentially pointing out of the layers and are antiferromagnetically coupled to the neighboring spins. Temperature ($T$) and magnetic field ($H$) dependent dielectric measurements indicated an apparent anomaly near ${T}_{\mathrm{N}}$, accompanied by a weak magnetodielectric effect. Raman mode renormalization and lattice anomalies near ${T}_{\mathrm{N}}$ demonstrated spin-lattice coupling through magnetoelastic and spin-phonon interactions. These findings highlight the fascinating interplay between spin, charge, and phonon degrees of freedom in ${\mathrm{Ni}}_{2}{\mathrm{Te}}_{3}{\mathrm{O}}_{8}$.