Single crystal growth and electronic structure of Fe-doped Sr₃Ir₂O₇

Metal–insulator transition (MIT) in perovskite iridium oxides Sr_n+1Ir_nO_3n+1 represents one of the most attractive phenomena exemplifying the cooperation of Coulomb interaction and spin–orbit coupling (SOC). MIT takes place when Sr_n+1Ir_nO_3n+1 (n = 1, 2) is doped with carriers. While electron-doped Sr_n+1Ir_nO_3n+1 (n = 1, 2) systems have been extensively investigated, hole-doped samples are still limited. Here, we report the first growth of Fe-doped (hole-doped) Sr₃Ir₂O₇ single crystals Sr₃(Ir_1−xFe_x)₂O₇ with the doping level 0.1 ≤ x ≤ 0.28. An MIT behavior is observed at the doping level of x ∼ 0.16 from resistivity measurements. Electronic structures of Fe-doped Sr₃Ir₂O₇ have been revealed by angle-resolved photoemission spectroscopy (ARPES) measurements. The evident energy shift of the band structure indicates higher hole-doping level as compared with Rh-doped Sr₃Ir₂O₇. Our results demonstrate that Fe doping serves as an effective approach for heavily hole doping in Sr₃Ir₂O₇, thereby offering a powerful strategy to modulate MIT in this material system.