Magnetism in PrIr2Si2: A single crystal study

We present the results of magnetization, susceptibility and specific-heat measurements of the high-temperature (HT) and low-temperature (LT) phases of PrIr₂Si₂ performed on single-crystalline samples. The HT and LT phases adopt the tetragonal CaBe₂Ge₂-type and ThCr₂Si₂-type structure, respectively. We have found no magnetic phase transition for the HT phase at temperatures down to 2 K. On the other hand, the LT phase apparently orders antiferromagnetically (AF) at 45.5 K and undergoes a transition to another AF phase at T_t=23.7 K. Complexity of the magnetic phase diagram is amplified by two metamagnetic transitions induced by magnetic field applied along the c-axis at temperatures below T_t. The results will be discussed with respect to other polymorphic compounds PrNi₂As₂ and UCo₂Ge₂.