Crystal structure and physical properties of the Sr-vacant spin-orbit-coupling induced Mott insulator Sr2−xIrO4

•According to the Raman analysis results, the modes of apical oxygen showing up in the frequency range of 500–800 cm−1 move towards the lower frequency obviously, which indicates the increasing of the apical Ir–O2 bond length. This is in good agreement with Rietveld analysis of the XRD data.•It can be seen from the temperature-dependent resistance that all the samples display a semiconducting feature in the wide temperature range in accordance with the 3D-VRH behavior.•The temperature-dependent magnetization reveals the magnetic anomalies around both 40 K and 180 K. Meanwhile, the curves exhibit antiferromagnetic properties under ZFC and FC conditions.

A series of polycrystalline samples of Sr2−xIrO4 (0≤x≤0.3) have been synthesized by a solid-state reaction method. The crystal structure of this doped system can be explained on the basis of the extended nature of 5d electrons and strontium vacancies in Sr2−xIrO4. The analysis of the temperature-dependent resistance of these samples reveals the semiconducting feature, in which the three-dimensional variable range hopping (3D-VRH) behavior is observed at temperatures lower than 120 K, the Arrhenius type in intermediate temperatures from 140 K to 200 K, and the two-dimensional (2D) weak-localization at high temperatures from 220 K to 300 K. Correspondingly, temperature-dependent magnetic properties in the range of x≤0.30 can be described by the antiferromagnetically ordered spin system.