Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada. Perimeter Institute for Theoretical Physics, 31 Caroline North, Waterloo, Ontario, N2L 2Y5, Canada. Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1Z8, Canada.
Rep Prog Phys. 2014 May;77(5):056501. doi: 10.1088/0034-4885/77/5/056501. Epub 2014 May 2.
The spin ice materials, including Ho2Ti2O7 and Dy2Ti2O7, are rare-earth pyrochlore magnets which, at low temperatures, enter a constrained paramagnetic state with an emergent gauge freedom. Spin ices provide one of very few experimentally realized examples of fractionalization because their elementary excitations can be regarded as magnetic monopoles and, over some temperature range, spin ice materials are best described as liquids of these emergent charges. In the presence of quantum fluctuations, one can obtain, in principle, a quantum spin liquid descended from the classical spin ice state characterized by emergent photon-like excitations. Whereas in classical spin ices the excitations are akin to electrostatic charges with a mutual Coulomb interaction, in the quantum spin liquid these charges interact through a dynamic and emergent electromagnetic field. In this review, we describe the latest developments in the study of such a quantum spin ice, focusing on the spin liquid phenomenology and the kinds of materials where such a phase might be found.
自旋冰材料包括 Ho2Ti2O7 和 Dy2Ti2O7，是稀土 pyrochlore 磁铁，在低温下进入具有新兴规范自由度的约束顺磁态。自旋冰提供了极少数实验实现分数化的例子之一，因为它们的基本激发可以被视为磁单极子，并且在某些温度范围内，自旋冰材料最好被描述为这些新兴电荷的液体。在量子涨落的存在下，原则上可以得到从经典自旋冰态衍生的量子自旋液体，其特征是出现类光子激发。虽然在经典自旋冰中，激发类似于具有库仑相互作用的静电电荷，但在量子自旋液体中，这些电荷通过动态和新兴的电磁场相互作用。在这篇综述中，我们描述了对这种量子自旋冰的最新研究进展，重点介绍了自旋液体现象学以及可能存在这种相的材料种类。
