Structural and magnetic ordering properties of TbFexMn12-x (x = 6.0–9.0) intermetallic compounds

In this work, single-phase TbFe _xMn _12-x compounds with the optimized composition (x = 6.0–9.0) were prepared, and their structural and magnetic ordering properties were investigated. It was found that the Tb-(Mn, Fe) coupling strength was significantly enhanced by the introduction of Fe, which finally significantly increased the magnetic ordering temperature of the R sublattice and induced interesting magnetic behaviors. When x ≤ 8.0, negative magnetization was observed in the M-T curves when decreasing the temperature in a constant positive external field. When x = 6.0, the M-T curve seemed the M-T curves of normal ferromagnetic materials because the net magnetization of the (Fe, Mn) magnetic sublattice was too small to induce the Tb magnetization to align in the opposite direction of the external magnetic field. Lateral and longitudinal offsets in the hysteresis loops, namely exchange-bias-like behavior, were observed, and with the increase of the maximum measurement field, the lateral and longitudinal offsets become smaller. The estimated minimum magnetic field required to cancel the offset was 110 kOe. In addition, AC susceptibility measurement results showed that all samples had the characteristics of spin-glass state at temperature just below the (Fe, Mn) sublattice ordering temperature due to the fluctuations in exchange interaction and anisotropy caused by the introduction of Fe in the (Fe, Mn) sublattice.