${\mathrm{Ni}}_3{\mathrm{TeO}}_6$ is a polar magnet with a pronounced magnetoelectric (ME) effect under high magnetic fields ($\approx 9\mathrm{T}$). Substitution of Ni with Co in ${\mathrm{Ni}}_3{\mathrm{TeO}}_6$ modulates the magnetic structure and reduces the critical field required to induce the ME response. In this study, we have grown single crystals of ${\mathrm{NiCo}}_2{\mathrm{TeO}}_6$ and measured the magnetic, dielectric, and magnetostriction properties. In addition, the temperature- and magnetic-field dependence of the dynamic ME coefficient (${\alpha }_{\mathrm{E}}=\mathrm{d}E/\mathrm{d}H$) was measured, enabling the construction of comprehensive ME phase diagrams. Pronounced peaks and dips in ${\alpha }_{\mathrm{E}}$ are observed at magnetic phase boundaries induced by temperature or magnetic field. Notably, the maximum ${\alpha }_{\mathrm{E}}$ is observed near the vicinity of the Néel temperature ($T_{\mathrm{N}}$) at a low magnetic field ($\approx 1.5\mathrm{T}$), in stark contrast with the high-field requirement in parent ${\mathrm{Ni}}_3{\mathrm{TeO}}_6$. Combined analysis of ${\alpha }_{\mathrm{E}}$ and magnetostriction data reveals that the anisotropic ME effect arises from the coexistence of spin-induced and magnetostriction-mediated polarization changes. These findings elucidate the intricate interplay among spin order, lattice strain, and electric polarization in ${\mathrm{NiCo}}_2{\mathrm{TeO}}_6$. Moreover, the combination of the dynamic ME coefficient and magnetostriction measurements provides a robust experimental framework for disentangling the microscopic origins of the ME effects.

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• Dielectric properties
• Magnetic phase transitions
• Magneto-dielectric effect
• Magnetic insulators
• Multiferroics