The behavior of the paradigmatic J1−J2 triangular lattice Heisenberg antiferromagnet in a magnetic field remains unsettled despite decades of study. We map out the phase diagram using three complementary approaches, including self-consistent nonlinear spin-wave theory, density-matrix renormalization group, and variational Monte Carlo. This combined analysis resolves the competition among different field-induced magnetic orders and magnetization plateaux across the classically frustrated parameter range. In particular, there is a finite range in the parameter regime around J2/J1=81 in which i) upon the application of the external field, the gapless quantum spin liquid acquires a finite density of monopoles, and ii) by further increasing the field, two plateaux are clearly obtained at m=31 and m=21. We discuss the experimental importance of the consecutive magnetization plateaux transitions as a signature of an underlying quantum spin-liquid phase.
@article{arxiv.2512.08768,
title = {Triangular $J_1$-$J_2$ Heisenberg Antiferromagnet in a Magnetic Field},
author = {Thomas Bader and Shi Feng and Sasank Budaraju and Federico Becca and Johannes Knolle and Frank Pollmann},
journal= {arXiv preprint arXiv:2512.08768},
year = {2025}
}