Sr₃LiIrO₆: a potential quantum spin liquid candidate in the one dimensional d⁴ iridate family

Spin-orbit coupling (SOC) offers a large variety of novel and extraordinary magnetic and electronic properties in otherwise 'ordinary pool' of heavy ion oxides. Here we present a detailed study on an apparently isolated hexagonal 2H spin-chain d⁴ iridate Sr₃LiIrO₆ (SLIO). Our structural studies clearly reveal perfect Li-Ir chemical order in this compound. Our combined experimental and ab-initio electronic structure investigations establish a magnetic ground state with finite Ir⁵+ magnetic moments in this compound, contrary to the anticipated nonmagnetic J=0 state. Furthermore, the dc magnetic susceptibility, ⁷Li nuclear magnetic resonance, heat capacity and spin-polarized density functional theory studies unravel that despite having noticeable antiferromagnetic correlation among the Ir⁵⁺ local moments, this SLIO system evades any kind of magnetic ordering down to at least 2 K due to geometrical frustration, arising from the comparable interchain Ir-O-O-Ir superexchange interaction strengths, hence promoting SLIO as a potential quantum spin liquid candidate. Finally, the linear temperature dependence of the magnetic specific heat at low temperatures in both zero and applied magnetic fields suggest a gapless spinon density of states in this potential QSL candidate Sr₃LiIrO₆.