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

In quantum spin liquid research, thin films are an attractive arena that enables the control of magnetic interactions via epitaxial strain and two-dimensionality, which are absent in bulk crystals. Here, as a promising candidate for the development of quantum spin liquids in thin films, we propose a robust ilmenite-type oxide with a honeycomb lattice of edge-sharing IrO₆ octahedra artificially stabilised by superlattice formation using the ilmenite-type antiferromagnetic oxide MnTiO₃. Stabilised sub-unit-cell-thick Mn–Ir–O layers are isostructural to MnTiO₃ and have an atomic arrangement corresponding to ilmenite-type MnIrO₃. By performing spin Hall magnetoresistance measurements, we observe that antiferromagnetic ordering in the ilmenite Mn sublattice is suppressed by modified magnetic interactions in the MnO₆ planes via the IrO₆ planes. These findings contribute to the development of two-dimensional Kitaev candidate materials, accelerating the discovery of exotic physics and applications specific to quantum spin liquids.