MAGNETOELECTRIC EFFECT AND LOW-TEMPERATURE PHASE-TRANSITIONS OF TBMN2O5

We made dielectric, magnetic and magnetoelectric measurements on single-crystal samples of ToMn(2)O(5), which was an antiferromagnet with the Neel temperature of approximately 40 K. From the results, we concluded that there were two groups of phase transitions at lower temperatures. The first group are three successive transitions at 29.3, 27.2 and 25.6 K, whose natures are probably electric. The crystal is polar below this temperature range, because the polarity of the magnetoelectric effect can be controlled by electric field cooling. Another transition exists at 8 K, where time inversion symmetry breaks. It is related to the ordering of Tb3+ magnetic moments.