论文标题
蜂窝J1-J2抗磁力Heisenberg模型的自旋动力学和连续光谱
Spin dynamics and continuum spectra of the honeycomb J1-J2 antiferromagnetic Heisenberg model
论文作者
论文摘要
我们采用自旋群集扰动理论来研究抗磁性$ j_ {1} $ - $ j_ {2} $ heisenberg模型在蜂窝晶格上的动力学特性。我们在相图中获得了所有可能阶段的激发光谱，包括Néel相，plaquette Valence-bond-solid相，二聚体价值 - 固定相和条纹抗fiferromagnetic相。在néel阶段，除了木元色散的明显重归于重新归一化之外，我们发现频谱在第二个布里渊区（BZ）附近表现出圆顶形的宽连续性，以及靠近BZ角落的额外的强连续性。在价键 - 固定阶段中，光谱一直以强大的连续体为主导，一直至低于$ j_1 $以下，与表征plaquette和二聚体相的最低能量的三位模式共存。我们将这种强大的宽连续体和额外的连续体归因于Néel阶段的BZ角接近分数Spinon激发的贡献。在条纹阶段，与线性自旋波近似的明显差异在于，由于强量量的波动，频谱被夹在$ m $点上，而后者获得的频谱是无间隙的。我们指出，在Néel阶段观察到的功能与Ybcl $ _ {3} $和ybbr $ _ {3} $的最新中子散射实验一致。
We employ the spin cluster perturbation theory to investigate the dynamical properties of the antiferromagnetic $J_{1}$-$J_{2}$ Heisenberg model on the honeycomb lattice. We obtain the excitation spectra for all possible phases in the phase diagram, including the Néel phase, plaquette valence-bond-solid phase, dimer valence-bond-solid phase and stripe antiferromagnetic phase. In the Néel phase, besides the obvious renormalization of the magnon dispersion, we find that the spectrum exhibits a dome-shaped broad continuum around the second Brillouin zone (BZ) and the additional strong continuum close to the corner of the BZ. In the valence-bond-solid phases, the spectra are dominated by a strong broad continuum all the way down to below $J_1$ coexisting with the lowest-energy triplon modes characterizing the plaquette and dimer phases. We ascribe this strong broad continuum and the additional continuum close to the BZ corner in the Néel phase to the contributions of fractionalized spinon excitations. In the stripe phase, a clear difference from the linear spin wave approximation is that the spectrum is gapped at the $M$ point while that obtained by the latter is gapless due to the strong quantum fluctuations. We point out that the features observed in the Néel phase are consistent with the recent neutron scattering experiments on YbCl$_{3}$ and YbBr$_{3}$.
