Non-Centrosymmetric Sr 2 IrO 4 Obtained Under High Pressure.

SrIrO with strong spin-orbit coupling and Hubbard repulsion (U) hosts Mott insulating states. The similar crystal structure and magnetic and electronic properties, particularly the -wave gap observed in SrIrO enhanced the analogies to the cuprate high- superconductor, LaCuO. The incomplete analogy was due to the lack of broken inversion symmetry phases observed in SrIrO. Here, under high-pressure and high-temperature conditions, we report a noncentrosymmetric SrIrO. The crystal structure and its noncentrosymmetric character were determined by single-crystal X-ray diffraction and high-resolution scanning transmission electron microscopy. The magnetic characterization confirms the Ir with = 1/2 at low temperature in SrIrO with magnetic ordering occurring at around 86 K, where a larger moment is observed than the ambient pressure SrIrO. Moreover, the resistivity measurement shows three-dimensional Mott variable-range hopping (VRH) existed in the system. This noncentrosymmetric SrIrO phase appears to be a unique material that offers a further understanding of high- superconductivity.