The impact of bi-phasic crystal structure on the magnetic and transport properties of single crystalline NdBaMn2O5+𝛿

Abstract

The LnBaMn2O5 (Ln = rare-earth) manganites have attracted considerable recent interest due to their potential for use as oxygen storage materials and as solid oxide fuel cells. However, there is scarce data on the magnetic properties of some prototypical materials. Here, we report the synthesis of a single-crystalline NdBaMn2O5+𝛿 compound by the floating-zone method and investigate its structural, electronic, and magnetic properties. The structural data indicate that, at room temperature, the material consists of a mixture of a NdBaMn2O5 phase with a layered arrangement of the Nd/Ba ions (space group 𝑃 4∕𝑛𝑚𝑚) and a NdBaMn2O6 phase with a disordered distribution of Nd/Ba (space group 𝐼𝑚𝑚𝑎). Measurements of magnetization performed with the magnetic field applied at distinct crystallographic directions reveal a rich magnetic diagram, which is compared with that of similar rare-earth manganites. A peculiar anisotropy is observed between the 𝑐 axis and the 𝑎𝑏 plane of the NdBaMn2O5 phase, suggesting a G-type magnetic structure in which the Mn moments are oriented along the 𝑎𝑏 planes. The electrical transport data show a pronounced magnetoresistance, which is discussed in terms of the system’s crystal structure and the presence of mixed-valent Mn.