Preparation and Characterization of a High-Entropy Magnet, (Mg, Mn, Co, Ni, Cu)3TeO6

We report on the synthesis of Mg0.6Mn0.7Co0.7Ni0.6Cu0.4TeO6, which is isostructural with multiferroic Mn3TeO6 (space group R 3 ). Study of its magnetic properties indicates establishment of the long-range antiferromagnetic order at 16.3 K, slightly lower than that of pure Mn3TeO6. The tiny hysteresis of magnetization loop along with specific heat data implies the presence of ferromagnetic magnons at low temperatures. Dielectric measurements reveal sequence of well-defined steps in the real part of permittivity and peaks in the imaginary parts of permittivity at 30, 92, and 212 K attributable to the highly diffused structural changes, which are characteristic to relaxor ferroelectrics. It is shown that usual interpretation of this structure type as corundum-related is not accurate: the hexagonal oxygen packing is not close and is not double-layered. Therefore, Mn3TeO6 represents a very special structure type.