Quantum Monte Carlo study of honeycomb antiferromagnets under a triaxial strain
Quantum Monte Carlo study of honeycomb antiferromagnets under a triaxial strain
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三轴应变下蜂窝状反铁磁体的量子蒙特卡罗研究
DOI：
10.1103/physrevb.104.125117
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发表时间：
2021-06
影响因子：
3.7
通讯作者：
Feng Shiping
中科院分区：
文献类型：
--
作者：
Sun Junsong;Ma Nvsen;Ying Tao;Guo Huaiming;Feng Shiping
用量子蒙特卡罗方法研究了蜂窝状反铁磁体在三轴应变下的运动.应变使拐角处的交换耦合二聚化，从而破坏了其中的反铁磁有序。反铁磁区不断减少的应变。对于相同的应变强度，精确的数值结果给出了一个比线性自旋波理论小得多的反铁磁区。然后，我们研究应变$XY$反铁磁体，磁振子赝磁场的行为完全不同。第0 $个朗道能级出现在谱的中间，其上（下）量子化能量与n^{\frac{1}{3}}（n^{\frac{2}{3}}）$成正比，这与海森堡情形中等间距的量子化能量形成了很大的对比。此外，我们还发现XY模型的反铁磁序对二聚化的鲁棒性比海森堡模型的强得多。用数值解析延拓方法求出了海森伯情形的局域磁化率，但没有发现伪朗道能级。目前尚不确定该结果是否是由于数值解析延拓的内在问题造成的。因此自旋$\frac{1}{2}$应变海森堡哈密顿量中磁振子赝朗道能级的存在性仍然是一个悬而未决的问题。我们的结果与二维货车德瓦耳斯量子反铁磁体密切相关，并有可能在实验上实现。
The honeycomb antiferromagnet under a triaxial strain is studied using the quantum Monte Carlo simulation. The strain dimerizes the exchange couplings near the corners, thus destructs the antiferromagnetic order therein. The antiferromagnetic region is continuously reduced by the strain. For the same strain strength, the exact numerical results give a much smaller antiferromagnetic region than the linear spin-wave theory. We then study the strained $XY$ antiferromagnet, where the magnon pseudo-magnetic field behaves quite differently. The $0$th Landau level appears in the middle of the spectrum, and the quantized energies above (below) it are proportional to $n^{\frac{1}{3}} (n^{\frac{2}{3}})$, which is in great contrast to the equally-spaced ones in the Heisenberg case. Besides, we find the antiferromagnetic order of the $XY$ model is much more robust to the dimerization than the Heisenberg one. The local susceptibility of the Heisenberg case is extracted by the numerical analytical continuation, and no sign of the pseudo-Landau levels is resolved. It is still not sure whether the result is due to the intrinsic problem of the numerical analytical continuation. Thus the existence of the magnon pseudo-Landau levels in the spin-$\frac{1}{2}$ strained Heisenberg Hamiltonian remains an open question. Our results are closely related to the two-dimensional van der Waals quantum antiferromagnets and may be realized experimentally.
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