Magnetization Plateaux as a Roadmap to Quantum Spin Liquids.

We investigate the spin-1/2 J_{1}-J_{2} triangular-lattice Heisenberg antiferromagnet in a magnetic field by combining large-scale density matrix renormalization group (DMRG) simulations with self-consistent spin-wave theory. The resulting field-coupling phase diagram reveals that quantum fluctuations stabilize coplanar order across the entire parameter range, giving rise to a characteristic sequence of magnetization plateaux. Near the quantum-spin-liquid window 0.06≲J_{2}/J_{1}≲0.16, which extends to magnetic field B∼J_{1}, we identify overlapping m=1/3 and m=1/2 plateaux-a distinctive hallmark of the system's proximity to the low-field spin-liquid regime. The excellent quantitative agreement between DMRG and self-consistent one-loop spin-wave calculations demonstrates that semiclassical approaches can reliably capture and parameterize the plateau phases of triangular quantum antiferromagnets.