Neutron powder diffraction study (T= 4.2-300 K) and polarization analysis of YBaCuFeO5+δ.

The crystal and magnetic structures of the perovskite YBaCuFeO5+δhave been studied in the temperature rangeT = 4.2-300 K by powder neutron diffraction. In addition to the antiferromagnetic ordering transition atTN = 442 K, a commensurate-incommensurate magnetic transition is detected atTN' = 190 K. Below this temperature, two sets of satellite peaks surround the (1/2,1/2,1/2) magnetic peak atd âˆ¼ Å, collapsing into a single set of satellites below 155 K. Polarization analysis has been performed to confirm the magnetic nature of the (1/2,1/2,1/2)±satellites.