Enhanced insulating state and diluted Ir4+ spin orders in Ir-vacant Sr2Ir1−xO4 systemsHuiting Yu, Shengli Liu, Bin Li, Haiyun Wang, Jie Cheng and Z. H. WangEPL, 120 2 (2017) 27007DOI: https://doi.org/10.1209/0295-5075/120/27007