Crystal Structure and Magnetic Properties of the Novel Compound ErMn5Ge3

The RE-M-Ge systems (RE: rare earths, M: transition group elements) contain a large number of compounds with special magnetic properties. A novel compound ErMn5Ge3 was found during the investigation on the phase diagram of the Er-Mn-Ge ternary system, and its crystal structure and magnetic properties were investigated. Powder X-ray diffraction results show that ErMn5Ge3 crystallizes in an orthorhombic YNi5Si3-type structure with the space group Pnma (No. 62) and the lattice parameters of a = 13.0524(6) Å, b = 3.8853(7) Å, and c = 11.4027(4) Å. The magnetization curves and isothermal magnetization curves from 100 to 300 K were measured for ErMn5Ge3. Magnetic tests showed that the compound was weakly magnetic and had a Curie temperature of 304 K. It is believed that its magnetic properties are determined by Mn atoms, which are surrounded by a complex environment, leading to uncertainty in the direction of the magnetic moment and hence poor magnetic ordering. This uncertainty simultaneously leads to a significant separation of the ZFC and FZ curves. First-principles calculations confirm that the magnetic properties of ErMn5Ge3 are mainly provided by the Mn atoms, and its magnetic moment is calculated to be about 4.5 μB. A possible magnetic structure model with simultaneous Mn-Mn ferromagnetic/antiferromagnetic coupling is constructed based on the Mn atom spacing, which can well explain the magnetic performance of ErMn5Ge3.