Field-induced transformation of ellipsoidal cycloidal to conical spin order and possible magnetoelectric effect in a triangular antiferromagnet MnGeTeO₆

The non-centrosymmetric layered honeycomb tellurate compound MnGeTeO₆ possesses a spin-frustrated triangular magnetic lattice, rendering it a compelling candidate for new multiferroic material. A high-quality MnTeGeO₆ polycrystalline sample was synthesized via solid-state synthesis. Magnetic and specific heat measurements confirmed an antiferromagnetic long-range ordered temperature (T_N) at 9.4 K, accompanying a metamagnetic phase transition observed in isothermal magnetization M (H) curves below T_N. Interestingly, a significant frequency-independent dielectric anomaly was observed near T_N in the temperature-dependent dielectric curves ε' (T). The scaling of magnetodielectric (MD) coupling with magnetization corresponds to the possible existence of higher-order magnetoelectric coupling. In this regard, the possible oblique conical type of spiral spin texture probably induces the observation of the higher-order magnetoelectric coupling, which underscores its substantial potential as a new magnetoelectric material.