Half moons are pinch points with dispersion
Half moons are pinch points with dispersion
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DOI：
10.1103/physrevb.98.140402
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发表时间：
2018-06
影响因子：
3.7
通讯作者：
Han Yan;Rico Pohle;N. Shannon
中科院分区：
文献类型：
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作者：
Han Yan;Rico Pohle;N. Shannon
“夹点”是在（准）弹性中子散射中观察到的奇异特征，是具有新兴规范对称性的自旋液体的一个广泛讨论的标志。人们对“半月”的关注要少得多，“半月”是有限能量下独特的新月图案，这种现象已在许多烧绿石磁体的实验和各种模型计算中观察到。在这里，我们将这两种现象统一在一个框架内，特别注意有序或场饱和状态的情况，其中可以在间隙上方的激发带中找到夹点和半月。我们发现半月只不过是刻在色散带上的夹点。 Kagome 晶格反铁磁体的分子动力学模拟用于探索这些能带如何演化为基态和经典自旋液体的激发。我们明确证明该理论可以重现在 Nd$_2$Zr$_2$O$_7$ 中观察到的夹点和半月。
"Pinch points," singular features observed in (quasi-)elastic neutron scattering, are a widely discussed hallmark of spin liquids with an emergent gauge symmetry. Much less attention has been paid to "half moons," distinctive crescent patterns at finite energy, which have been observed in experiments on a number of pyrochlore magnets, and in a wide range of model calculations. Here we unify these two phenomena within a single framework, paying particular attention to the case of ordered, or field-saturated states, where pinch points and half moons can be found in bands of excitations above a gap. We find that half moons are nothing other than pinch points inscribed on a dispersing band. Molecular dynamics simulations of the kagome lattice antiferromagnet are used to explore how these bands evolve into the ground state and excitations of a classical spin liquid. We explicitly demonstrate that this theory can reproduce the pinch points and half moons observed in Nd$_2$Zr$_2$O$_7$.