Crystal Structure and Magnetic Properties of HfFe₆Ge₆-Type ErMn_6–xCo_xGe₆ (x = 0–1.45) Alloys

Abstract

Ternary intermetallic compounds RMn6Ge6 with complex magnetic phase transitions are expected to be developed and applied in spintronic storage and computing devices in the future. The relationship between the crystal structure and physical properties (electrical conductivity, thermal analysis, and complex magnetic transformation) of ErMn6–x Co x Ge6 (x = 0–1.45) alloys was studied in the range of 80–600 K. The result shows that the polycrystalline alloys crystallize in the hexagonal HfFe6Ge6 type (P 6/mmm). Co doping causes orbital hybridization between Co 2p, Mn 2p, and Er 4d and leads to the presence of mixed valence states of Mn3+ and Mn4+, leading to complex magnetic behaviors: the alloys display a Néel point at a high temperature T N (∼500 K), magnetization increases again at T C (∼250 K), and a second peak in the temperature dependence of magnetization at about T t (∼150 K), which is spin reorientation. We discuss these phenomena in terms of Mn–Mn, Er–Mn, and Mn3+/Mn4+ and the prospect for potential applications of the studied alloy in magneto memory and new topological kagome magnet fields.