We investigate the spin-1/2 J1−J2 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≲J2/J1≲0.14, which extends to magnetic field B∼J1, 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.
@article{arxiv.2512.02150,
title = {$J_1-J_2$ Triangular Lattice Antiferromagnet in a Magnetic Field},
author = {Anna Keselman and Xinyuan Xu and Hao Zhang and Cristian D. Batista and Oleg A. Starykh},
journal= {arXiv preprint arXiv:2512.02150},
year = {2025}
}