Non-centrosymmetric Sr$_{2}$IrO$_{4}$ obtained under High Pressure

TL;DR

This study reports the synthesis of a non-centrosymmetric phase of Sr$_{2}$IrO$_{4}$ under high pressure, revealing new structural and magnetic properties that could advance understanding of high-$T_c$ superconductivity.

Contribution

The paper demonstrates the creation of a non-centrosymmetric Sr$_{2}$IrO$_{4}$ phase using high pressure, providing new insights into its structure and magnetic behavior.

Findings

Non-centrosymmetric Sr$_{2}$IrO$_{4}$ synthesized under high pressure.

Magnetic ordering occurs at around 86 K with a larger magnetic moment.

Resistivity indicates three-dimensional Mott variable-range hopping.

Abstract

Sr$_{2}$IrO$_{4}$ 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 Sr$_{2}$IrO$_{4}$ enhanced the analogies to cuprate high-$T_{c}$ superconductor, La$_{2}$CuO$_{4}$. The incomplete analogy was due to the lack of broken inversion symmetry phases observed in Sr$_{2}$IrO$_{4}$. Here, under high pressure and high temperature conditions, we report a non-centrosymmetric Sr$_{2}$IrO$_{4}$. 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 Ir$^{4+}$ with $S$ = 1/2 at low temperature in Sr$_{2}$IrO$_{4}$ with magnetic ordering occurred at around 86 K, where a larger moment is observed than the ambient pressure Sr$_{2}$IrO$_{4}$. Moreover, the resistivity measurement shows three-dimensional Mott variable-range hopping existed in the system. This non-centrosymmetric Sr$_{2}$IrO$_{4}$ phase appears to be a unique material to offer further understanding of high-$T_{c}$ superconductivity.