New Kitaev Magnet with Compelling Thermodynamic Evidence of Proximity to the Kitaev Spin-Liquid*

Kitaev magnets are widely studied in search of quantum spin-liquid (QSL) ground states and Majorana excitations. Recent theoretical studies predict two potential signatures of a QSL at finite temperatures: a scaling behavior of thermodynamic quantities and a two-step release of the magnetic entropy. Here, we successfully synthesized a new Kitaev magnet, Ag₃LiIr₂O₆ with both signatures in our AC magnetic susceptibility, magnetization and heat capacity measurements. In this new quaternary oxide, despite the existence of a large Weiss temperature, there is no evidence of long-range order in our DC magnetic susceptibility and heat capacity measurements. Based on our DFT calculations, a mixing between silver d and oxygen p orbitals enhances the spin-orbit coupling within the honeycomb layers suggesting a closer proximity to the QSL in Ag₃LiIr₂O₆ compared to known Kitaev magnets, α-Li₂IrO₃ and Na₂IrO₃.