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arXiv · 2512.02150

$J_1-J_2$ Triangular Lattice Antiferromagnet in a Magnetic Field

Anna Keselman·Xinyuan Xu·Hao Zhang·Cristian D. Batista·Oleg A. Starykh
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Abstract

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 $0.06 \lesssim J_2/J_1 \lesssim 0.14$, which extends to magnetic field $B \sim J_1$, 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.

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Anna Keselman, Xinyuan Xu, Hao Zhang, Cristian D. Batista, Oleg A. Starykh. 2025-12-01. $J_1-J_2$ Triangular Lattice Antiferromagnet in a Magnetic Field. https://arxiv.org/abs/2512.02150

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