On J_eff=0 Ground State Iridates(V): Tracking Residual Paramagnetism in New Bi₂NaIrO₆

Abstract

Open-shell transition metal oxides are capable of developing a rich diversity of electronic phases. The specific features evolving crucially depend on an intricate interplay of various local and long-range electronic interactions. Recently, the 5d transition elements have come into sharp focus because for these elements spin-orbit coupling (SOC) and onsite Coulomb repulsion (U) are on a comparable energy scale. For Ir the t level associated to an octahedral crystal field (CF) is split by SOC, giving rise to a J = spin state and rendering respective oxides like Sr IrO as Mott insulators. Transferring this scenario to iridium(V) oxides would lead to a diamagnetic ground state, J =0. However, reported experimental results do not lend unambiguous support for such an electronic state. Theoretical explanations for the breakdown of the J=0 magnetic state suffer from conspicuous discrepancies. In an attempt to empirically contribute to resolving the puzzle, Bi NaIrO was synthesized in high purity by precipitation from homogeneous solution; it represents an iridium(V) oxide where long range band structure effects and magnetic superexchange are minimized, and the t degeneracy is lifted geometrically. We managed to reduce the strength of paramagnetic response, lending support to a J =0 ground state of Bi NaIrO , exhibiting van Vleck type behavior.

New Ag8PtO6: synthesis, crystal structure, physical properties and theoretical analyses

“…with Ir 5+ oxides. 12 Applying density functional band structure calculations, we can clearly assign a 5d 6 6s 0 configuration to the Pt atoms, consistent with a non-magnetic state.…”

Na9Bi5Os3O24: A Diamagnetic Oxide Featuring a Pronouncedly Jahn–Teller‐Compressed Octahedral Coordination of Osmium(VI)

“…This has been encountered for 5 d 4 ions like Ir 5+ . [ 14 , 15 ] Also for Os 6+ (5 d 2 ) a nonmagnetic ground state owing to a combined action of spin‐orbit coupling and cubic crystal field (10 Dq ) has been reported. [ 16 , 17 , 18 ] The character of this state, however, is distinctly different from what we have in Na 9 Bi 5 Os 3 O 24 : it is not a singlet state with S = 0 , but a non‐Kramers e g doublet.…”

Charge transfer energy in iridates: a hard x-ray photoelectron spectroscopy study

“…Single crystals of Ba 2 YIrO 6 , Sr 2 YIrO 6 , and Bi 2 NaIrO 6 and polycristalline samples of Sr 2 FeIrO 6 , and SrLaBIrO 6 with B=(Ni, Zn) were grown following the procedures as described in the literature [8,9,16,17,36].…”

“…For compounds with the formal Ir 5+ valency, the analogous picture leaves the j ef f = 3/2 bands fully filled while the j ef f = 1/2 doublet remains empty, producing a Van Vleck singlet ground state with J ef f = 0 [8][9][10]. Interestingly, a theoretical study presented yet the possibility of the presence of excitonic magnetism in such systems [11], and some experimental studies reported also FIG.…”