Coexistence of Magnetoelectric and Antiferroelectric-like Orders in Mn₃Ta₂O₈

In materials showing a linear magnetoelectric (ME) effect, unconventional functionalities can be anticipated such as electric control of magnetism and nonreciprocal optical responses. Thus, the search for new linear ME materials is of interest in materials science. Here, using a recently proposed design principle of linear ME materials, which is based on the combination of local structural asymmetry and collinear antiferromagnetism, we demonstrate that an anion-deficient fluorite derivative, Mn₃Ta₂O₈, is a new linear ME material. This is evidenced by the onset of magnetic-field-induced electric polarization in its collinear antiferromagnetic phase below T_N = 24 K. Furthermore, we also find an antiferroelectric-like phase transition at T_S = 55 K, which is attributable to an off-center displacement of magnetic Mn²⁺ ions. The present study shows that Mn₃Ta₂O₈ is a rare material that exhibits both ME and antiferroelectric-like transitions. Thus, Mn₃Ta₂O₈ may provide an opportunity to investigate the physics associated with complicated interactions between magnetic (spin) and electric dipole degrees of freedom.