Non-centrosymmetric Sr₂IrO₄ obtained under high pressure

Sr₂IrO₄ with strong spin-orbit coupling (SOC) and Hubbard repulsion (U) hosts Mott insulating states. The similar crystal structure and electronic properties observed enhance its analogies to the high-T_c superconductive cuprates, La₂CuO₄ family. Here we report a non-centrosymmetric Sr₂IrO₄ phase (Sr₂IrO₄-HP) synthesized at 6 GPa and 1400 °C. Sr₂IrO₄-HP crystallizes into the tetragonal space group I4mm without an inversion center. The crystal structure and its non-centrosymmetric character were determined by single crystal X-ray diffraction (SCXRD) and high-resolution scanning transmission electron microscopy (HR-STEM). Our magnetic characterization indicates there is a significant suppression of Néel temperature to around 86 K, with a larger moment observed than ambient pressure Sr₂IrO₄. Moreover, the resistivity measurement suggests three-dimensional Mott variable-range hopping existed in the system. This non-centrosymmetric Sr₂IrO₄-HP appears to be a unique material to offer a further possible understanding of high-T_c superconductivity.