Physical properties and phase diagram of single crystal REBaMn2O6 (RE = Sm, Eu, Gd, Tb, Dy, and Y)

We have carried out a systematic study on antiferromagnetic and charge ordering phase transitions in double-perovskite manganite compounds REBaMn2O6 (RE 1/4 Sm, Eu, Gd, Tb, Dy, and Y) by using single-crystalline samples. In YBaMn2O6, a tiny anomaly near 480 K as well as a first-order phase transition near 520 K are found in the temperature dependence of resistivity. Synchrotron x-ray single-crystal structure analysis shows that the unit cell is doubled first in the ab plane and further doubled along the c-axis as the temperature decreases. One of the most possible electronic phases between 480 K and 520 K is Zener polaron ordering. Mn atoms are paired in the ab-plane with seven 3d-electrons localized on each pair. The 3d-electron distribution in each pair begins to become asymmetric below 480 K. Similar two-step transitions are also observed for RE 1/4 Tb and Dy. The antiferromagnetic transition at TN ' 180 K is accompanied by a large hysteresis, which is attributable to a simultaneous rearrangement of charge order. The charge rearrangement temperature gradually rises with increasing the RE ionic radius. In SmBaMn2O6, the Ne?el temperature (TN) is 175 K and is lower than charge rearrangement temperature (' 200 K). These transitions are summarized in a phase diagram with respect to temperature and the ionic radius of RE3 + .

Automated summary

The study systematically investigates the antiferromagnetic and charge ordering phase transitions in double-perovskite manganite compounds. It reveals interesting phenomena such as temperature dependence, cell doubling, and asymmetric electron distribution.