Rare-earth intermetallics play a critical yet often obscure role in numerous technological applications, including sensors, actuators, permanent magnets, and rechargeable batteries; therefore, understanding their basic science is of utmost importance. Here we report structural behaviors, specific heat, and magnetism of $\mathrm{P}{\mathrm{r}}_{1\text{–}x}\mathrm{E}{\mathrm{r}}_x\mathrm{A}{\mathrm{l}}_2$ studied by means of temperature-dependent x-ray powder diffraction, heat capacity, and magnetization measurements, in addition to first-principles calculations. Although the cubic lattice of $\mathrm{PrA}{\mathrm{l}}_2$ distorts tetragonally at the Curie temperature $T_C$, the distortion is rhombohedral in $\mathrm{ErA}{\mathrm{l}}_2$, creating a potential for instability in the pseudobinary $\mathrm{PrA}{\mathrm{l}}_2\text{−}\mathrm{ErA}{\mathrm{l}}_2$ system. When $0.05\le x\le 0.5$, materials show complex magnetization behaviors, including metamagnetic transitions and Griffith-like phase. Unique among other mixed-lanthanide dialuminides, the substitution of Er for Pr in $\mathrm{P}{\mathrm{r}}_{1\text{–}x}\mathrm{E}{\mathrm{r}}_x\mathrm{A}{\mathrm{l}}_2$ results in unexpected ferrimagnetic behavior, and the ferrimagnetic interactions become strongest around $x=0.25$, where the compound shows unusual metamagnetic like transitions observed only in the odd-numbered quadrants of the full magnetic field cycles. The electronic structure calculations, including exchange interactions and crystal field splitting, magnetic moments, anisotropic $4f$ energy density, and magnetic surface potentials rationalize the interesting physics observed experimentally.

• Received 5 October 2016

DOI:https://doi.org/10.1103/PhysRevB.94.224406