High-temperature magnetic anomaly via suppression of antisite disorder through synthesis route modification in a...

By incorporating inert KCl into the Na₂IrO₃+ 2CuCl → Cu₂IrO₃+ 2NaCl topochemical reaction, we significantly reduced the synthesis temperature of Cu₂IrO₃from the 350 °C reported in previous studies to 170 °C. This adjustment decreased the Cu/Ir antisite disorder concentration in Cu₂IrO₃from ∼19% to ∼5%. Furthermore, magnetic susceptibility measurements of the present Cu₂IrO₃sample revealed a weak ferromagnetic-like anomaly with hysteresis at a magnetic transition temperature of ∼70 K. Our research indicates that the spin-disordered ground state reported in chemically disordered Cu₂IrO₃is an extrinsic phenomenon, rather than an intrinsic one, underscoring the pivotal role of synthetic chemistry in understanding the application of Kitaev model to realistic materials.