Crystal and magnetic structures of the Ir(V) JeffIr = 0 double perovskite LaSrNiIrO6

The Co2＋-Ir5＋ orbital hybridization in LaCaCoIrO6 double perovskite

“…The straight line represents the best fit of the paramagnetic region of the curve with the Curie-Weiss (CW) law, from which we obtain χ 0 = 3.9 × 10 −4 emu/mol•Oe, with this value being in the range usually found for Ir 5+ -based DPs [5,28,43]. The negative sign of the CW temperature extracted from the fit, θ CW = -74 K, indicates a predominance of AFM coupling in LCCIO, in agreement with other DPs containing a 3d TM ion and Ir 5+ such as LaSrNiIrO 6 , Sr 2 FeIrO 6 , and Sr 2 CoIrO 6 , for which it is attributed an AFM arrangement of the 3d ions, with the Ir 5+ being presumably in the J = 0 state [10,15,28]. Despite our low-temperature magnetization being somewhat larger than what is observed in the materials mentioned above, it remains considerably lower than the value expected for FM or even FIM arrangements.…”

“…As a result, the conventional Goodenough-Kanamori-Anderson rules often fail to describe the magnetic coupling between the TM ions [7,8,9]. A recent study on LaSrNiIrO 6 , for instance, has shown an antiferromagnetic (AFM) superstructure at the Ni 2+ site through the Ni 2+ -O-Ir 5+ -O-Ni 2+ path [10]. On the other hand, the complete substitution of Sr 2+ by a rare-earth A 3+ element in A 2 NiIrO 6 DPs leads to a magnetic Ir 4+ state, which couples AFM with the Ni 2+ ions to produce a ferrimagnetic (FIM) behavior whose strength increases as the A-site ionic radius decreases [11].…”

Crystal structure and properties of the magnetically frustrated B‐site ordered Sr2CaOsO6 double perovskite

“…For the late 5 d transition elements these quantities arrive at a particular constellation insofar as the energies of related SOC, crystal field (CF), bandwidth ( W ), and electron correlation ( U ) fall into a narrow range, which together with respective chemical environments give rise to conspicuous and diverse electronic and magnetic ground states in solid materials. Among them phenomena like the Kitaev scenario, J eff =0 magnetic ground state for Ir 5+ , Mott insulating states and superconductivity arising from it have been predicted and experimentally realized [1–8] …”

“…Among them phenomena like the Kitaev scenario, J eff = 0 magnetic ground state for Ir 5 + , Mott insulating states and superconductivity arising from it have been predicted and experimentally realized. [1][2][3][4][5][6][7][8] So far, most of the theoretical as well as experimental studies have been conducted on iridates and only to a lesser extent on osmates. In this context, the 5d 2 electron configuration of osmium(VI), embedded in an oxide matrix, continues to attract particular attention.…”