Unveiling emergent magnetic excitations in the trimer-based quantum spin liquid candidates Ba4NbM3O12 (M=Ir, Rh)

The recently discovered hexagonal perovskite Ba4NbM3O12 provides a new platform to investigate a quantum spin liquid (QSL) state, in which the magnetic building block M3O12 form a triangular lattice (TL) via the non-magnetic NbO6 in the ab-plane. Therefore, Ba4NbM3O12 harbors the complex dimensional magnetic nature of magnetism due to the TL (2D) composed of the coupled trimers (0D). One of the series compounds, Ba4NbM3O12 (M=Ir, Rh), is considered as the promising QSL candidates, evidenced by the magnetic susceptibility and heat capacity measurements. In addition, it is revealed that the substitution of the M-site provides a pathway to control the spin-orbit coupling (SOC), leading to the stabilization of the QSL state. Therefore, Ba4NbM3O12 (M=Ir, Rh) is an ideal system to investigate QSL physics as well as the effects of the SOC on the trimer-based TL with the crossover of magnetism.