Field-tunable quantum disordered ground state in the triangular-lattice antiferromagnet NaYbO₂

Antiferromagnetically coupled $S=1/2$ spins on an isotropic triangular lattice are the paradigm of frustrated quantum magnetism, but structurally ideal realizations are rare. Here, we investigate NaYbO₂, which hosts an ideal triangular lattice of effective $J_{\text{eff}}=1/2$ moments with no inherent site disorder. No signatures of conventional magnetic order appear down to 50 mK, strongly suggesting a quantum spin liquid ground state. We observe a two-peak specific heat and a nearly quadratic temperature dependence, in agreement with expectations for a two-dimensional Dirac spin liquid. Application of a magnetic field strongly perturbs the quantum disordered ground state and induces a clear transition into a collinear ordered state, consistent with a long-predicted up-up-down structure for a triangular-lattice XXZ Hamiltonian driven by quantum fluctuations. The observation of spin liquid signatures in zero field and quantum-induced ordering in intermediate fields in the same compound demonstrates an intrinsically quantum disordered ground state. We conclude that NaYbO₂ is a model, versatile platform for exploring spin liquid physics with full tunability of field and temperature.