Effect of Ce doping on the structural, transport and magnetic properties of Sr₂IrO₄ epitaxial films

Sr₂IrO₄ is predicted to be superconducting and has received extensive attention in the field of high-temperature superconducting. Bulk Sr₂IrO₄ can be converted to a metallic state by slight chemical doping. Here we studied the structure, morphology, transport and magnetism of (Sr_1−xCe_x)₂IrO₄ (x = 0, 0.0125, 0.025, 0.05) epitaxial films grown on (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.35 substrates. Unlike the bulk Sr₂IrO₄ material, the doped Sr₂IrO₄ epitaxial film maintains a wide range of Mott variable-range hopping characteristics in transport. Meanwhile, the magnetic properties and Raman characteristic peaks of the doped films become weakened, and the degree of weakening is proportional to the doping concentration. These observations can be attributed to the localization caused by disorder after Ce doping and the presence of structural defects. The epitaxial strain may result in important differences between Sr₂IrO₄ epitaxial thin films and bulk single crystals.