- Review Article
Spin-orbit effects in heavy 5d transition metal oxides, in particular, iridates, have received enormous current interest due to the prediction as well as the realization of a plethora of exotic and unconventional magnetic properties. While a bulk of these works are based on tetravalent iridates (d (5)), where the counter-intuitive insulating state of the rather extended 5d orbitals are explained by invoking strong spin-orbit coupling, the recent quest in iridate research has shifted to the other valencies of Ir, of which pentavalent iridates constitute a notable representative. In contrast to the tetravalent iridates, spin-orbit entangled electrons in d (4) systems are expected to be confined to the J = 0 singlet state without any resultant moment or magnetic response. However, it has been recently predicted that, magnetism in d (4) systems may occur via magnetic condensation of excitations across spin-orbit-coupled states. In reality, the magnetism in Ir5+ systems are often quite debatable both from theoretical as well as experimental point of view. Here we provide a comprehensive overview of the spin-orbit coupled d (4) model systems and its implications in the studied pentavalent iridates. In particular, we review here the current experimental and theoretical understanding of the double perovskite (A (2) BYIrO6, A = Sr, Ba, B = Y, Sc, Gd), 6H-perovskite (Ba-3 MIr2O9, M = Zn, Mg, Sr, Ca), post-perovskite (NaIrO3), and hexagonal (Sr-3 MIrO6) iridates, along with a number of open questions that require future investigation. Show more
Journal / seriesJournal of Physics: Condensed Matter
Pages / Article No.
Subjectspin orbit coupling; oxides; iridates; magnetism
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