Crystal structure and physical properties of the Sr-vacant   spin-orbit-coupling induced Mott insulator Sr2-xIrO4
  A series of polycrystalline samples of Sr2-xIrO4 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, where three dimensional variable range hopping behavior is observed at temperatures lower than 120K, Arrhenius type in intermediate temperatures from 140K to 200K, and two-dimensional (2D) weak localization at high temperatures from 220K to 300K. Correspondingly, temperature-dependent magnetic properties in the range of x less than 0.30 can be described by the antiferromagnetically ordered spin system. 
Jimei Kong, S. L. Liu, Jie Cheng, Haiyun Wang, Xing ao Li, Z. H. Wang
cond-mat.str-el