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

Abstract

We have successfully synthesized the novel antiferromagnets with Ir 4+ 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 MgIrO3 and ZnIrO3 up to 60T show different behaviors, demonstrating that each magnetic ground state is different with each other. We discuss the difference in the ground state between MgIrO3 and ZnIrO3 from the viewpoint a magnetic model consisting of the Kitaev and Dzyaloshinskii-Moriya interactions with the spin frustration effect on the honeycomb lattice.

Electronic and magnetic properties of iridium ilmenites $A$IrO$_3$ ($A=$ Mg, Zn, and Mn)

“…We find that the ab-AFM state has the lowest energy in the whole range of U Ir , except for U Ir = 0 where the system is a paramagnetic metal (see below). The result is consistent with the experiment where the magnetic susceptibility shows the easy-plane anisotropy [19]. We note, however, that the energy difference between the ab-AFM and c-AFM state is not large and becomes smaller for larger U Ir .…”

“…We adopt the fully-relativistic and non-relativistic projector-augmented-wave-method Perdew-Zunger type pseudopotentials for the A and B-site ions and the O ligands, respectively [44][45][46]. While we employ the experimental structural data for MnTiO 3 [47] and for MgIrO 3 and ZnIrO 3 [19], we perform structural optimization for the fictitious compound MnIrO 3 starting from the experimental structure for MnTiO 3 with replacement of Ti by Ir; we relax not only the atomic positions within the primitive unit cell but also the lattice translation vectors. In the optimization, we set the minimum ionic displacement to 0.001 A in the Broyden-Fletcher-Goldfarb-Shanno iteration scheme [48].…”

“…Since the iridium ilmenites have a similar honeycomb network, they potentially serve as another candidates for the Kitaev spin liquid. Powder samples of these compounds, however, were shown to exhibit magnetic phase transitions at 31.8 K for MgIrO 3 , 46.6 K for ZnIrO 3 [19], and 90.9 K in CdIrO 3 [20], which are higher than ∼ 15 K for AIrO 3 [22,23,[37][38][39]. The susceptibility measurements for the A = Mg and Zn indicate that they have in-plane magnetic anisotropy, while Na 2 IrO 3 and Li 2 IrO 3 show the out-of-plane and in-plane anisotropy, respectively [22,28].…”

“…Recently, a new series of ilmenite with B=Ir has been synthesized as MgIrO 3 , ZnIrO 3 , and CdIrO 3 [19,20]. These compounds are of particular interest from a different perspective than ATiO 3 : they have a honeycomb network of edge-sharing IrO 6 octahedra similar to monoclinic A 2 IrO 3 with A = Na and Li which have been intensively studied as candidates for realizing a quantum spin liquid in the honeycomb Kitaev model [21][22][23][24][25][26][27][28][29][30][31].…”

Stabilization of a honeycomb lattice of IrO6 octahedra by formation of ilmenite-type superlattices in MnTiO3

“…This is because their volatile and/or diffusible nature requires the precise control of stoichiometry and the suppression of inter-diffusion to reproduce the bulk properties. Inspired by these problems in known Kitaev candidate materials, we aim to determine a new crystal system that is suitable for thin-film research and focus on ilmenite-type ABO 3 compounds (where A and B are metal cations) containing Ir 19,20 . Recently, Haraguchi et al proposed a method for the bulk synthesis of ilmenite-type ZnIrO 3 and MgIrO 3 with honeycomb lattices of edge-sharing IrO 6 octahedra in the ab plane 19 (e.g., see Fig.…”