Magnetic Coulomb fields of monopoles in spin ice and their signatures in the internal field distribution.
Magnetic Coulomb fields of monopoles in spin ice and their signatures in the internal field distribution.
复制标题
自旋冰中单极子的库仑磁场及其内场分布特征。
DOI：
10.1103/physrevlett.108.217203
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发表时间：
2012
影响因子：
8.6
通讯作者：
Sala G
中科院分区：
文献类型：
--
作者：
Sala G
分割化是多体物理学中最违反直觉的现象之一，它是一个明显不可分割的微观自由度的分裂。在这里，我们研究它在自旋冰中最基本的表现，自旋冰是已知的唯一3D分馏磁性化合物：我们直接可视化随着原子磁偶极子分馏而出现的磁单极子的磁库仑场。我们分析了与局部实验探头相关的内部磁场分布。特别是，我们提出了新的零场核磁共振测量，与计算的线形显示出很好的一致性，指出这种实验技术原则上可以直接测量自旋冰中的单极密度。场强的分布是通过一种简单的分析形式捕捉到的，该形式显示了低密度的低场位置--这显然与已报道的Muon自旋旋转结果不一致。与直觉相反的是，低场位置的密度随着冰规则强加的局部铁磁关联减弱而减少。
Fractionalization—the breaking up of an apparently indivisible microscopic degree of freedom—is one of the most counterintuitive phenomena in many-body physics. Here we study its most fundamental manifestation in spin ice, the only known fractionalized magnetic compound in 3D: we directly visualize themagnetic Coulomb field of monopoles that emerge as the atomic magnetic dipoles fractionalize. We analyze the internal magnetic field distribution, relevant for local experimental probes. In particular, we present new zero-field NMR measurements that exhibit excellent agreement with the calculated line shapes, noting that this experimental technique can in principle measure directly the monopole density in spin ice. The distribution of field strengths is captured by a simple analytical form that exhibits a low density of low-field sites—in apparent disagreement with reported muon spin rotation results. Counterintuitively, the density of low-field locations decreases as the local ferromagnetic correlations imposed by the ice rules weaken.