Hybridization effects on the magnetic ground state of ruthenium in double perovskite LaZnRuTiO.

An exotic quantum mechanical ground state, i.e. the non-magnetic= 0 state, has been predicted for higher transition metalt2g4systems, due to the influence of strong spin-orbit coupling (SOC) or in other words, due to unquenched orbital moment contribution. However, previous attempts to experimentally realize such a state in 5systems had mostly been clouded by solid-state effects or the reduced strength of the renormalized SOC that might allow significant triplon condensation. Interestingly, a recent study on vacancy ordered double perovskite compound KRuClby Takahashi(2021227201) concluded that even withincoupling regime the Ru4ions, within isolated RuCloctahedra, strongly accommodatemultiplets having= 0 as the ground state with weakly interacting= 1 excitation, due to large unquenced Ru orbital angular momentum in the system. In the present report, we show results from the double perovskite LaZnRuO, where Ruions form isolated RuOoctahedra but unlike KRuCl, they remain chemically connected via corner-sharing with nonmagnetic ZnOoctahedra. Next, we move on to separate out the RuOoctahedra further by doping the Ru-site with Ti, in order to probe the character of the Ruions within a different structural background. We find that the system stabilizes in21/nspace group with tilted octahedra without distortion as has been confirmed by the x-ray powder diffraction and x-ray absorption spectroscopic studies. Interestingly, the x-ray photoelectron spectroscopic valance band spectra indicated certain inhomogeneity around the half-doping region, while confirming insulating ground state for all. Moreover, unlike the vacancy ordered double perovskite cases, it is observed that here the Ru orbital angular momentum gets substantially quenched and only the Ru spin magnetic moments are realized.