Possibility to realize spin-orbit-induced correlated physics in iridium fluorides

Abstract

Recent theoretical predictions of "unprecedented proximity" of the electronic ground state of iridium fluorides to the SU(2) symmetric j eff = 1/2 limit, relevant for superconductivity in iridates, motivated us to investigate their crystal and electronic structure. To this aim, we performed highresolution x-ray powder diffraction, Ir L3-edge resonant inelastic x-ray scattering, and quantum chemical calculations on Rb2[IrF6] and other iridium fluorides. Our results are consistent with the Mott insulating scenario predicted by Birol and Haule [Phys. Rev. Lett. 114, 096403 (2015)], but we observe a sizable deviation of the j eff = 1/2 state from the SU(2) symmetric limit. Interactions beyond the first coordination shell of iridium are negligible, hence the iridium fluorides do not show any magnetic ordering down to at least 20 K. A larger spin-orbit coupling in iridium fluorides compared to oxides is ascribed to a reduction of the degree of covalency, with consequences on the possibility to realize spin-orbit-induced strongly correlated physics in iridium fluorides.

Spin-orbit entangled j=12 moments in Ba2CeIrO6 : A frustrated fcc quantum magnet

“…In Ba 2 CeIrO 6 , the peaks are located at about 0.61 eV and 0.71 eV, both at 10 K and at 300 K. The observation of two peaks signals non-cubic local distortions in agreement with our analysis of the x-ray diffraction data. A fit using two peaks with the Pearson VII line shape [36] that mimics a convolution of an intrinsic Lorentzian line shape and a Gaussian profile with the experimental resolution yields a splitting ∆ exp = (100 ± 4) meV, the smallest splitting reported thus far in L edge RIXS for the spin-orbit exciton in iridates [27][28][29][30][31]35]. The peak values of 0.61 eV and 0.71 eV allow for two different solutions of Eq.…”

Hopping-Induced Ground-State Magnetism in 6H Perovskite Iridates

“…However, most striking is the substantially suppressed value of SOC (∼ 0.26 eV) compared to any other iridate reported as yet, proving the decisive role of intra-dimer hopping in these systems. In this context, reduced covalency has recently been ascribed to increased SOC in iridium fluorides [30]. RIXS of these 6H-iridates provide first clear experimental evidences of atomic non-magnetic SOC J = 0 state breakdown, in presence of solid state effects.…”

Cubic symmetry and magnetic frustration on the fcc spin lattice in K2IrCl6

“…In the absence of any additional crystal-field splitting, spin-orbit coupling separates the t 2g states into the lower-lying j eff = 3 2 and higher-lying j eff = 1 2 manifolds, with the latter forming a half-filled band gapped by even moderate electronic correlations [1]. This general scenario has been exemplified in more than a dozen of iridates studied over the last decade [2], although the symmetry of Ir 4+ is usually lower than cubic, thus leading to crystal-field splittings within the t 2g shell [3,4] or, in cases like CaIrO 3 [5,6] and Sr 3 CuIrO 6 [7], even to profound deviations from the j eff = 1 2 scenario. The quest for cubic systems based on Ir 4+ is triggered by interesting predictions for the magnetic interactions that would arise in this setting [1,8].…”