Antiferromagnetism in Two-Dimensional, 1T-Phase Iridium Oxide

Theoretical studies show that metastable phases of nonmagnetic oxides could exhibit magnetic order when synthesized in two-dimensional (2-D) atomic crystals. In this letter, we report experimental evidence of a nontrivial antiferromagnetic behavior in a 2-D, metastable phase of iridium oxide in which iridium forms a triangular lattice. We compare the magnetic behavior of the crystals in the morphology of 2-D nanosheets with that of the same crystals in the morphology of nanoparticles. At low temperatures, the magnetic moment of nanosheets exceeds that of the nanoparticles while coercivity and remanence collapse, suggesting a transition to an antiferromagnetic phase. Morphology at the nanoscale seems to play a significant role in the magnetic behavior of oxide semiconductors.