The delafossitelike compound ${\mathrm{NaYbO}}_2$ hosts a triangular lattice of ${\mathrm{Yb}}^{3+}$ moments and is a promising candidate for the realization of a quantum spin liquid ground state—an exotic, quantum-disordered magnetic phase featuring long-range entanglement of spins. Tuning this system away from this quantum-disordered regime toward classical order or spin freezing is a powerful approach to shed light on the nature of the parent ground state. Here we leverage the substitution of nonmagnetic ${\mathrm{Lu}}^{3+}$ onto the ${\mathrm{Yb}}^{3+}$ sites to study the effects of magnetic disorder in ${\mathrm{NaYbO}}_2$ using low-temperature ac susceptibility, heat capacity, and muon spin relaxation ($\mu \mathrm{SR}$) measurements. Our $\mu \mathrm{SR}$ measurements reveal resilient, correlated magnetic fluctuations that persist to at least 15% dilution, precluding conventional spin freezing and magnetic inhomogeneity. Heat capacity and magnetic susceptibility resolve a rapid suppression of the field-induced “up-up-down” magnetic order upon dilution and a crossover in the power-law behavior of the low-temperature magnetic excitations associated with the zero-field quantum disordered ground state. Taken together, these results support the notion of a robust network of entangled moments in ${\mathrm{NaYbO}}_2$ and provide experimental validation of several models of a Heisenberg triangular lattice antiferromagnet in the presence of disorder.

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• Quantum spin liquid
• Rare-earth magnetic materials
• Triangular lattice
• Muon spin relaxation & rotation