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The structural and magnetic properties of Pr-alloyed MnBi (short MnBi-Pr) nanostructures with a range of Pr concentrations are investigated. The nanostructures include thin films having Pr concentrations 0, 2, 3, 5 and 9 at.% and melt-spun ribbons having Pr concentrations 0%, 2%, 4% and 6%, respectively. Addition of Pr into the MnBi lattice has produced a significant change in the magnetic properties of these nanostructures including an increase in coercivity and structural phase transition temperature, and a decrease in saturation magnetization and anisotropy energy. The highest value of coercivity measured in the films is 23 kOe and in the ribbons is 5.6 kOe. The observed magnetic properties are explained as the consequences of competing ferromagnetic and antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

High-anisotropy arc-melted and field-annealed Mn100−xBix (x  =  50–65) alloys have been investigated. Samples predominantly consist of low-temperature phase (LTP) MnBi and elemental Bi, where the LTP volume fraction and sample magnetization decrease with increasing x. All samples are hard ferromagnetic at room temperature and demonstrate a structural and magnetic phase transition at 630 K. For Mn35Bi65, the highest values for coercivity (4.6 kOe), magnetization remanence ratio (0.97), and energy product (4.9 MGOe) are measured at 540 K, near the melting point of bismuth. We explain the trend in magnetic properties as a consequence of c-axis alignment of MnBi grains facilitated by the molten Bi during magnetic field annealing. [ABSTRACT FROM AUTHOR]