Fluctuating magnetism in Zn-doped averievite with well-separated kagome layers

Kagome lattice decorated with S = 1 / 2 spins is one of the most discussed ways to realize a quantum spin liquid. However, all previous material realizations of this model have suffered from additional complications, ranging from additional interactions to impurity effects. Recently, a new quantum kagome system has been identified in the form of averievite Cu 5 − x Zn x V 2 O 10 (CsCl), featuring a unique double-layer spacing between the kagome planes. Using muon spin spectroscopy we show that only a complete substitution (i.e., x = 2 ) of interplanar copper ions leads to a quantum-disordered ground state. In contrast, the parent compound ( x = 0 ) exhibits long-range magnetic order, with a phase transition around 24 K. Experiments performed on the partially substituted material ( x = 1 ) show that the transformation proceeds through an intermediate disordered, partially frozen ground state, unaffected by pressures up to 23 kbar. Our study provides a microscopic view of the magnetism of the decoupling of the kagome layers and establishes the averievite as a new material platform for the experimental study of the fully-decoupled kagome layers.