Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y5.
Department of Physics and Astronomy, University of Waterloo, Ontario, Canada N2L 3G1.
Nat Commun. 2015 Jun 22;6:7421. doi: 10.1038/ncomms8421.
Actively sought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at zero temperature. Despite ongoing searches, QSLs remain elusive, due to a lack of concrete knowledge of the microscopic mechanisms that inhibit magnetic order in materials. Here we study a model for a broad class of frustrated magnetic rare-earth pyrochlore materials called quantum spin ices. When subject to an external magnetic field along the [111] crystallographic direction, the resulting interactions contain a mix of geometric frustration and quantum fluctuations in decoupled two-dimensional kagome planes. Using quantum Monte Carlo simulations, we identify a set of interactions sufficient to promote a groundstate with no magnetic long-range order, and a gap to excitations, consistent with a Z2 spin liquid phase. This suggests an experimental procedure to search for two-dimensional QSLs within a class of pyrochlore quantum spin ice materials.
自本世纪初以来，人们一直在积极寻找二维量子自旋液体（QSL），这是一种物质的奇特相，其中磁矩即使在零温度下也保持无序。尽管人们一直在寻找，但由于对抑制材料磁有序的微观机制缺乏具体的了解，QSL 仍然难以捉摸。在这里，我们研究了一类被称为量子自旋冰的广泛的受挫磁稀土烧绿石材料的模型。当在[111]晶体学方向上施加外磁场时，所产生的相互作用包含了几何受挫和在解耦二维 kagome 平面上的量子涨落的混合。通过量子蒙特卡罗模拟，我们确定了一组相互作用，足以促进没有磁长程有序的基态，以及与 Z2 自旋液体相一致的激发能隙。这表明了一种实验方法，即在一类烧绿石量子自旋冰材料中寻找二维 QSL。
