Magnetic structures of high-temperature multiferroic compound YBa(Cu1-xMnx)FeO5

YBaCuFeO5 has two magnetic transitions: The spin system orders to a collinear structure at TN1, and it changes at TN2 to incommensurate spiral structure accompanied with a ferroelectricity and multiferroic. Recently, it reported that TN2 of YBaCuFeO5 can be increased above 310 K through a controlled manipulation of the Cu/Fe chemical disorder. We have investigated the magnetic properties of YBaCu1-xMnxFeO5, because doped Mn ions induce the Cu/Fe chemical disorder. We found that the TN2 can be raised by Mn-doping above 350 K. The two magnetic transitions become one at x = 0.05, and two transitions appear again above x = 0.05, In order to understand the origin of these magnetic transitions, we request 4 days on the WISH diffractometer to collect the neutron magnetic reflection intensities from the four samples YBaCu1-xMnxFeO5 (x=0, 0.03, 0.05 and 0.07).