Magnetic order and magnetic properties of the oxygen deficient SmBaMn2O5 layered perovskite

•SmBaMn2O5 exhibits a checker board pattern of compressed and expanded MnO5 pyramids due to the condensation of a breathing mode.•The magnetic structure of SmBaMn2O5 has been determined thanks to the use of hot neutrons.•The magnetic structure is ferrimagnetic with the Mn moments align antiparallel along the c axis.•The polarization of Sm moments leads to a change in the direction of the easy magnetization axis below 10 K.