Seeing the light: Experimental signatures of emergent electromagnetism in a quantum spin ice
Seeing the light: Experimental signatures of emergent electromagnetism in a quantum spin ice
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DOI：
10.1103/physrevb.86.075154
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发表时间：
2012-08-30
影响因子：
3.7
通讯作者：
Shannon, Nic
中科院分区：
文献类型：
--
作者：
Benton, Owen;Sikora, Olga;Shannon, Nic
在稀土烧绿石磁体Ho2Ti2O7和Dy2Ti2O7中发现的“自旋冰”状态提供了经典静磁学的美丽实现，并完成了磁共振激发。有人提出，在“量子自旋冰”材料中，不同冰结构之间的量子力学隧穿可以将自旋冰的静磁转换为量子自旋液体，实现量子电磁学的完全动力学晶格模拟。在这里，我们将探索这样一种状态如何在实验中表现出来，在这样一个量子自旋冰的最小微观模型中。我们为这个模型开发了一个晶格场理论，并使用它来明确预测量子自旋冰上中子散射实验中观察到的动态结构因子。我们发现，“夹点”，这是一个经典的自旋冰的信号特征，消失的量子冰冷却到零温度的基态。我们还明确预测幽灵般的，线性分散的磁激发，这是“光子”的出现电磁。这个场理论的预测被证明是在定量协议与量子蒙特卡罗模拟在零温度。
The "spin-ice" state found in the rare-earth pyrochlore magnets Ho2Ti2O7 and Dy2Ti2O7 offers a beautiful realization of classical magnetostatics, complete with magnetic monopole excitations. It has been suggested that in "quantum spin-ice" materials, quantum-mechanical tunneling between different ice configurations, could convert the magnetostatics of spin ice into a quantum spin liquid that realizes a fully dynamical, lattice analogue of quantum electromagnetism. Here, we explore how such a state might manifest itself in experiment, within the minimal microscopic model of a such a quantum spin ice. We develop a lattice field theory for this model, and use this to make explicit predictions for the dynamical structure factor that would be observed in neutron scattering experiments on a quantum spin ice. We find that "pinch points," which are the signal feature of a classical spin ice, fade away as a quantum ice is cooled to its zero-temperature ground state. We also make explicit predictions for the ghostly, linearly dispersing magnetic excitations which are the "photons" of this emergent electromagnetism. The predictions of this field theory are shown to be in quantitative agreement with quantum Monte Carlo simulations at zero temperature.