The physical properties of $\mathrm{BaCoT}{\mathrm{e}}_2{\mathrm{O}}_7$ single crystals were investigated using magnetization, magnetostriction, electron spin resonance, and electric polarization under static and pulsed high magnetic fields. Experimental results reveal that single-crystal sample is an antiferromagnet at low temperatures, with an effective pseudospin $S_{\mathrm{eff}}$ of 1/2 and a relatively large anisotropic effective $g$ factor, which originates from the lowest Kramers doublet of $\mathrm{C}{\mathrm{o}}^{2+}$ with dominant $|S_z|=3/2$ character under strong spin-orbit coupling. When a magnetic field is applied along the easy magnetization $c$ axis, two successive magnetic phase transitions ($H_{\mathrm{c}1}$ and $H_{\mathrm{c}2}$) were observed, between the two critical fields, the Co ions with a ↑↑↑↓ spin configuration correspond to a 1/2 magnetization plateau. At critical field $H_{\mathrm{c}1}$, spins rotate from parallel (antiparallel) to nearly perpendicular to the magnetic field, at $H_{\mathrm{c}2}$, a change occurs from a ferrimagnetic state to a high-field coplanar spin configuration. Magnetostriction measurements indicate significant anisotropic spin-lattice coupling in $\mathrm{BaCoT}{\mathrm{e}}_2{\mathrm{O}}_7$. First-principles calculations based on the four-state method reveal comparable antiferromagnetic nearest-neighbor and next-nearest-neighbor exchange interactions ($J_{\mathrm{NN}}=-10.76$ meV and $J_{\mathrm{NNN}}=-9.33$ meV), which imply strong competing interactions and exchange frustration in the zigzag Co network of $\mathrm{BaCoT}{\mathrm{e}}_2{\mathrm{O}}_7$. The exchange interactions between the $\mathrm{Co}\cdots \mathrm{Co}$ bonds in the noncollinear spin configuration (with a canted ↑↑↓↓ spin arrangement) induced by the magnetic field give rise to inequivalent exchange coupling, resulting in the emergence of net electric dipole moments. Through analysis of the multistep transitions induced by pulsed magnetic fields in the block-ordered antiferromagnetic state, combined with magnetostriction and polarization measurements, and supported by the large exchange energy scale relative to the Néel temperature, the multiferroic behavior of $\mathrm{BaCoT}{\mathrm{e}}_2{\mathrm{O}}_7$ can be understood in terms of an exchange striction mechanism associated with its noncollinear spin order.

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• Crystal growth
• High magnetic fields
• Magnetic phase transitions
• Magneto-dielectric effect
• 1-dimensional spin chains
• Magnetic insulators
• Multiferroics
• Noncollinear magnets
• Electron spin resonance
• Magnetization measurements