Abstract
Single crystals of and have been successfully grown using hydroxides flux. and crystallize in the structure with the space group (no. 167). and are electrically insulating with estimated activation gaps of 0.68 and 0.80 eV, respectively. and show paramagnetic behavior down to 2 K. In this work, the observed effective moments, , for single crystals are for and for , which are much smaller than that of previously reported for the polycrystalline samples. For single crystals, a much larger value of is observed as compared with single crystals. The x-ray absorption spectroscopy and low-temperature specific heat data indicate that the Ir in has an almost pure valence state, while the Ir in is slightly lower than +5. The estimated low limits of magnetic impurity are about ∼1.7% and ∼9.2% for and , respectively. These magnetic impurities are likely to fully explain the observed values for and single crystals, supporting the ground state of in and .
- Received 26 July 2022
- Accepted 22 September 2022
DOI:https://doi.org/10.1103/PhysRevMaterials.6.094415
©2022 American Physical Society