Preparation and magnetic and electrical properties of EuBaMn2O6−δ (δ=0,1)

The EuBaMn2O6 composition prepared in air at T=1500°C is shown to be a cubic perovskite exhibiting spin-glass properties below Tf=40 K. The reduced composition, EuBaMn2O5, crystallizes in a perovskite-like, YBaCuFeO5-type layered structure with a tetragonal unit cell. EuBaMn2O5 with crystallographically ordered Eu3+ and Ba2+ ions is a ferromagnet with TN=160 K. The anomalous behavior of the paramagnetic susceptibility is assumed to be due to a partial ordering of the Mn2+ and Mn3+ ions. EuBaMn2O5 oxidized in air at 900°C to EuBaMn2O6 has a magnetic ordering temperature TM=260 K, near which the magnetoresistance reaches a peak value. X-ray diffraction measurements show the long-range order in the Eu3+ and Ba2+ ion arrangement to persist in the oxidized EuBaMn2O6 sample.