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arXiv · 1611.06920

Quantum phase transitions in Heisenberg $J_1-J_2$ triangular antiferromagnet in a magnetic field

Mengxing Ye·Andrey V. Chubukov
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Abstract

We present the zero temperature phase diagram of a Heisenberg antiferromagnet on a frustrated triangular lattice with nearest neighbor ($J_1$) and next nearest neighbor ($J_2$) interactions, in a magnetic field. We show that the classical model has an accidental degeneracy for all $J_2/J_1$ and all fields, but the degeneracy is lifted by quantum fluctuations. We show that at large $S$, for $J_2/J_1 <1/8$, quantum fluctuations select the same sequence of three sublattice co-planar states in a field as for $J_2 =0$, and for $1/8 1$, the transition remains first order, with a finite hysteresis width, but for $S=1/2$ and, possibly, $S=1$, there appears a new intermediate phase, likely without a spontaneous long-range order.

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Mengxing Ye, Andrey V. Chubukov. 2016-11-21. Quantum phase transitions in Heisenberg $J_1-J_2$ triangular antiferromagnet in a magnetic field. https://doi.org/10.1103/physrevb.95.014425

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