The ternary intermetallic compound, ${\text{Pr}}_6{\text{Ni}}_2{\text{Si}}_3$, is a member of a structure series of compounds based on a triangular structure where the number of Pr atoms in the prism cross section can be systematically varied. ${\text{Pr}}_6{\text{Ni}}_2{\text{Si}}_3$ contains two distinct Pr lattice sites which result in complex interactions between the magnetic ions. Extensive measurements of specific heat and magnetization on single-crystal samples indicate that ${\text{Pr}}_6{\text{Ni}}_2{\text{Si}}_3$ orders with both a ferromagnet and an antiferromagnet component, with ordering temperatures of 39.6 and $\sim 32\text{K}$, respectively. The ferromagnetic component $\parallel$ $c$ axis is accompanied by a large hysteresis, and the antiferromagnetic component $\perp$ $c$ axis is accompanied by a spin-flop-type transition. More detailed measurements, of the vector magnetization, indicate that the ferromagnetic and the antiferromagnetic order appear independent of each other. These results not only clarify the behavior of ${\text{Pr}}_6{\text{Ni}}_2{\text{Si}}_3$ itself but also of the other members of the structure series, ${\text{Pr}}_5{\text{Ni}}_2{\text{Si}}_3$ and ${\text{Pr}}_{15}{\text{Ni}}_7{\text{Si}}_{10}$.

• Received 8 January 2008

DOI:https://doi.org/10.1103/PhysRevB.77.214407