A comparative study on magnetic order and field-induced magnetic transition in double perovskite iridates: REZnIrOand REMgIrO(RE = Pr, Nd, Sm, Eu, Gd).

We perform a comparative magnetic study on two series of rare-earth (RE) based double perovskite iridates REBIrO(RE = Pr, Nd, Sm-Gd; B = Zn, Mg), which show Mott insulating state with tunable charge energy gap from ∼330 meV to ∼560 meV by changing RE cations. For nonmagnetic RE = Eu cations, EuMgIrOshows antiferromagnetic (AFM) order and field-induced spin-flop transitions below Néel temperature () in comparison with the ferromagnetic (FM)-like behaviors of EuZnIrOat low temperatures. For magnetic-moment-containing RE ions, GdBIrOshow contrasting magnetic behaviors with FM-like transition (B = Zn) and AFM order (B = Mg), respectively. While, for RE = Pr, Nd and Sm ions, all members show AFM ground state and field-induced spin-flop transitions belowirrespective of B = Zn or Mg cations. Moreover, two successive field-induced metamagnetic transitions are observed for REZnIrO(RE = Pr, Nd) in high field up to 56 T, the resultant field temperature (-) phase diagrams are constructed. The diverse magnetic behaviors in REBIrOreveal that the 4-Ir exchange interactions between the RE and Ir sublattices can mediate their magnetism.