Pseudosymmetry in Tetragonal Perovskite SrIrO$_3$ Synthesized under High Pressure

TL;DR

This paper reports the synthesis of a tetragonal SrIrO3 perovskite under high pressure, revealing complex structural features, weak paramagnetism, and metallic behavior with low-temperature anomalies, contributing to understanding of iridate materials.

Contribution

It introduces a novel high-pressure synthesis method for tetragonal SrIrO3 and characterizes its unique structural and physical properties.

Findings

Tetragonal SrIrO3 synthesized at 6 GPa and 1400°C

Weak paramagnetic behavior observed down to 2 K

Metallic resistivity with low-temperature upturn

Abstract

In this study, we report a tetragonal perovskite structure of SrIrO$_3$ (P4/mmm, a = 3.9362(9) \r{A}, c = 7.880(3) \r{A}) synthesized at 6 GPa and 1400 $\deg$C, employing the ambient pressure monoclinic SrIrO$_3$ with distorted 6H structure as a precursor. The crystal structure of tetragonal SrIrO3 was evaluated on the basis of single crystal and powder X-ray diffraction. A cubic indexing was observed attributed to overlooked superlattice reflections. Weak fractional peaks in the H and K dimensions suggest possible structure modulation by oxygen defects. Magnetization study reveals weak paramagnetic behavior down to 2 K, indicative of the interplay between spin-orbit coupling, electron correlations, and crystal electric field. Additionally, measurements of electrical resistivity display metallic behavior with an upturn at about 54 K, ascribed to weak electron localization and possible structural defects.