Successive Phase Transitions in a Metal-Ordered Manganite Perovskite YBaMn2O6

Structural, magnetic and electric properties of a metal-ordered perovskite YBaMn2O6 have been studied by means of powder X-ray diffraction, DSC, magnetic susceptibility, and electric resistivity. It is found that this material undergoes a 1st order structural phase transition at Tc1=520 K, from a pseudo orthorhombic (monoclinic) phase to a pseudo tetragonal (monoclinic) one. Accompanied by this transition, the susceptibility exhibits a sharp drop, where ferromagnetic exchange interaction becomes antiferromagnetic. Furthermore, two more transitions, a metal-insulator transition at Tc2=480 K and an antiferromagnetic ordering at Tc3=200 K, have been observed respectively.