Magnetic ordering with an XY-like anisotropy in the honeycomb lattice iridates ZnIrO3 and MgIrO3 synthesized via a metathesis reaction

We have successfully synthesized the novel antiferromagnets with Ir4+ honeycomb lattice ZnIrO3 and MgIrO3 and investigated their magnetic and thermodynamic properties. The two iridates are isomorphic but exhibit qualitatively different magnetic properties. ZnIrO3 shows antiferromagnetic ordering below 46.6 K, whereas MgIrO3 displays weak ferromagnetic behavior below 31.8 K, owing to formation of a canted antiferromagnetic ordering. The measurement of magnetic susceptibility with using an oriented powder sample revealed the presence of an XY-like magnetic anisotropy and a tilting magnetic structure which is possibly stabilized by the Kitaev interaction. Moreover, magnetization curves of ZnIrO3 and MgIrO3 up to 60 T show different behaviors, demonstrating that each magnetic ground state is different with each other. We discuss the difference in the ground state between ZnIrO3 and MgIrO3 from the viewpoint a magnetic model consisting of the Kitaev and Dzyaloshinskii-Moriya interactions with the spin-frustration effect on the honeycomb lattice.