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, magnetic and electronic properties, particularly the d-wave gap observed in Sr₂IrO₄ enhanced the analogies to cuprate high-$T_c$ superconductor, La₂CuO₄. The incomplete analogy was due to the lack of broken inversion symmetry phases observed in Sr₂IrO₄. Here, under high pressure and high temperature conditions, we report a non-centrosymmetric Sr₂IrO₄. The crystal structure and its noncentrosymmetric character were determined by single crystal X-ray diffraction and high-resolution scanning transmission electron microscopy (HR-STEM). The magnetic characterization confirms the Ir⁴⁺ with $\\textit{S}$ = 1/2 at low temperature in Sr₂IrO₄ with magnetic ordering occurred at around 86 K, where a larger moment is observed than the ambient pressure Sr₂IrO₄. Moreover, the resistivity measurement shows three-dimensional Mott variable-range hopping existed in the system. Further, this non-centrosymmetric Sr₂IrO₄ phase appears to be a unique material to offer further understanding of high-$T_c$ superconductivity.