Emergent phases in Kitaev spin-orbital magnets

磁性材料在手机和计算机的信息存储以及电力的产生和分配方面的技术进步中起着核心作用。然而，当磁性通过量子效应在这些材料中被抑制时，一种被称为“量子自旋液体”的全新物质阶段就出现了。该奖项支持对量子自旋液相材料的理论研究。在量子自旋液相中，即使在绝对零度下，量子自旋也没有固定的排列顺序，并且永远波动。这种材料显示出不同寻常的特性，可能具有技术意义，例如为量子计算提供平台的可能性。在这个项目中，PI和他的团队将研究被称为Kitaev自旋轨道模型的量子自旋液体的新模型。该团队将从理论上设计出能够展示自旋液相的新材料，并与实验学家合作，以确定这些材料的关键实验特征。除了凝聚态理论的研究生培训外，该奖项还将支持PI的推广工作，包括促进量子素养-理解量子物理的基本原理-在高中水平。为了实现这一目标，PI将参与“科学与工程体验”和“亚利桑那州科学俱乐部”高中拓展计划，指导高中生，并为他们组织专注于量子世界的讲习班。该奖项支持理论研究，旨在研究单层和双层基塔耶夫自旋轨道模型，作为实现对外部扰动稳定的量子自旋液体的新平台。虽然蜂窝晶格上的Kitaev模型是第一个具有量子自旋液体基态的精确可解模型，但由于量子自旋液体状态对实际材料中存在的额外相互作用很脆弱，因此该模型直接应用于实际材料受到限制。解决这个问题的一个方法是将基塔耶夫模型扩展到它的自旋轨道泛化，通常称为基塔耶夫自旋轨道模型。双层基塔耶夫自旋轨道模型的研究工作将集中于通过互补分析方法估计层间交换和小角度扭转的相图。PI还将进行蒙特卡罗模拟，以研究通过附加相互作用稳定的视觉晶体（通量激发的周期性排列）。成功的结果将为即将到来的量子自旋液体实验提供关键的见解，同时促进我们对基塔耶夫模型的自旋轨道推广的理解。除了凝聚态理论的研究生培训外，该奖项还将支持PI的推广工作，包括促进量子素养-理解量子物理的基本原理-在高中水平。为了实现这一目标，PI将参与“科学与工程体验”和“亚利桑那州科学俱乐部”高中拓展计划，指导高中生，并为他们组织专注于量子世界的讲习班。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYMagnetic materials play a central role in technological advancements in information storage in cell phones and computers as well as creation and distribution of electricity. However, when the magnetism is suppressed in these materials via quantum effects, a completely new phase of matter called "quantum spin liquid" appears. This award supports theoretical research on materials exhibiting the quantum spin liquid phase, in which the quantum spins do not order in a fixed configuration even at absolute zero temperature and perpetually fluctuate. Such materials show unusual properties that may have technological implications such as the possibility of offering a platform for quantum computation. In this project, the PI and his team will investigate new models of quantum spin liquids called Kitaev spin-orbital models. The team will theoretically design new materials that can exhibit spin liquid phase and collaborate with experimentalists for the identification of the key experimental signatures of these materials. In addition to graduate student training in condensed matter theory, this award will also support the PI's outreach efforts that involve promoting quantum literacy - understanding the fundamentals of quantum physics - at the high school level. To achieve this goal, the PI will participate in the ‘Science and Engineering Experience’ and ‘Clubes de Ciencia Arizona’ high school outreach programs to mentor high school students and organize workshops for them focused on the quantum world.TECHNICAL SUMMARYThis award supports theoretical research with an aim to investigate single- and bi-layer Kitaev spin-orbital models as new platforms for the realization of quantum spin liquids that are stable to external perturbations. While the Kitaev model on the honeycomb lattice is the first exactly solvable model with a quantum spin liquid ground state, direct application of this model to real materials is limited as the quantum spin liquid state is fragile to additional interactions present in real materials. One way to remedy this challenge relies on extending the Kitaev model to its spin-orbital generalization, commonly called Kitaev spin-orbital models. The research activities in bilayer Kitaev spin-orbital models will focus on estimating the phase diagram as a function of interlayer exchange and small angle twisting via complementary analytical methods. The PI will also perform Monte Carlo simulations to investigate vison crystals (periodic arrangement of flux excitations) that are stabilized by additional interactions. Successful outcomes will provide key insights to upcoming experiments on quantum spin liquids while advancing our understanding of spin-orbital generalizations of Kitaev model. In addition to graduate student training in condensed matter theory, this award will also support the PI's outreach efforts that involve promoting quantum literacy - understanding the fundamentals of quantum physics - at the high school level. To achieve this goal, the PI will participate in the ‘Science and Engineering Experience’ and ‘Clubes de Ciencia Arizona’ high school outreach programs to mentor high school students and organize workshops for them focused on the quantum world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.