Kitaev interactions through extended superexchange pathways in the j eff = 1 / 2 Ru 3+ honeycomb magnet RuP 3 SiO 11

Magnetic materials are composed of the simple building blocks of magnetic moments on a crystal lattice that interact via magnetic exchange. Yet from this simplicity emerges a remarkable diversity of magnetic states. Some reveal the deep quantum mechanical origins of magnetism, for example, quantum spin liquid (QSL) states in which magnetic moments remain disordered at low temperatures despite being strongly correlated through quantum entanglement. A promising theoretical model of a QSL is the Kitaev model, composed of unusual bond-dependent exchange interactions, but experimentally, this model is challenging to realise. Here we show that the material requirements for the Kitaev QSL survive an extended pseudo-edge-sharing superexchange pathway of Ru octahedra within the honeycomb layers of the inorganic framework solid, RuP SiO . We confirm the requisite state of Ru in RuP SiO and resolve the hierarchy of exchange interactions that provide experimental access to an unexplored region of the Kitaev model.