Quantum Magnetism in Rare-Earth Honeycomb Lattices

稀土蜂窝晶格中的量子磁性

• 批准号: 2005143
• 负责人: James Neilson
• 金额: $ 31.06万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2005143&HistoricalAwards=false
• 关键词: Quantum; Magnetism; Rare; Earth; Honeycomb

Non-technical abstract: “Quantum materials” are those which have unusual properties arising from the quantum mechanical nature of electrons in solids. In quantum magnets, it is the spin of the electrons which are engaged in this quantum behavior. Quantum magnets often host wildly dynamic spins at very low temperatures, and can be manipulated to form new quantum phases of matter under various conditions, such as in a strong applied magnetic field. Through this project, new quantum magnetic materials are synthesized and studied in such extreme environments, with the goal of finding new quantum magnetic phenomena, like a quantum spin liquid. The materials studied here are based on rare-earth elements, which have traditionally been overlooked as key ingredients for quantum magnets, but in reality give a much wider range of possibilities for quantum behavior compared to traditional materials design approaches. This work focuses on rare-earth based materials in which the spins are arranged into a graphene-like geometry called the honeycomb lattice. The magnetic behavior of these materials is explored in detail using a wide range of advanced techniques, such as neutron scattering. This project advances the understanding of quantum many-body systems and highlights new ways in which they can be realized in nature. It also contributes to the training of highly qualified personnel in the methods of materials synthesis and characterization. The training of the future generation of materials scientists, particularly those well-versed in quantum phenomena, is essential for future paradigm-shifting advances in materials research. Technical Abstract:Rare-earth based honeycomb lattice materials are an unconventional class of quantum magnets. Due to the presence of strongly quantum fluctuating spins, in combination with anisotropic interactions arising from strong spin-orbit coupling, these materials can host a different set of quantum phases than can be achieved in traditional (3d transition-metal based) quantum magnets. This project will investigate a range of phenomena which have been found to manifest in rare-earth based honeycomb lattice materials, including quantum dimer magnetism leading to field-induced Bose Einstein condensation, Ising-like quantum criticality, and promising avenues to realize the highly entangled Kitaev quantum spin liquid. The project involves the synthesis of bulk samples of rare-earth honeycomb materials, with particular emphasis on single-crystal growth. These materials are characterized by thermodynamic probes and inelastic neutron scattering. Thermodynamics gives a road map of the phase diagrams, while inelastic neutron scattering enables the understanding of the emergent quasi-particle excitations and their evolution with varying applied magnetic field. The relatively weak interaction energies of rare-earth materials enables the use of a powerful method of determining the interaction parameters in these materials, via theoretical modeling of field-polarized inelastic neutron scattering spectra. This work has relevance to a broad range of other areas of physics research, such as superfluid helium in porous media, superconductivity, and ultra-cold atomic gases. The impacts of this work also extend beyond many-body quantum physics; through this project, students who are part of underrepresented minority groups in physics, are encouraged to explore the concept of magnetism and phase transitions in materials and to gain hands-on research experience.This Division of Materials Research (DMR) grant supports research to understand a range of phenomena which have been found to manifest in rare-earth based honeycomb lattice materials with funding from the Condensed Matter Physics (CMP) Program in DMR of the Mathematical and Physical Sciences Directorate.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.

非技术摘要：“量子材料”是那些具有不寻常的性质，从量子力学性质的电子在固体。在量子磁体中，参与这种量子行为的是电子的自旋。量子磁体通常在非常低的温度下拥有疯狂的动态自旋，并且可以在各种条件下（例如在强磁场中）被操纵以形成物质的新量子相。通过该项目，在这种极端环境下合成和研究新的量子磁性材料，目的是发现新的量子磁性现象，如量子自旋液体。这里研究的材料基于稀土元素，传统上被忽视为量子磁体的关键成分，但实际上，与传统材料设计方法相比，它为量子行为提供了更广泛的可能性。 这项工作的重点是稀土基材料，其中自旋被安排成一个石墨烯样的几何形状称为蜂窝晶格。这些材料的磁性行为进行了详细探讨，使用广泛的先进技术，如中子散射。该项目推进了对量子多体系统的理解，并突出了它们在自然界中实现的新方法。它还有助于在材料合成和表征方法方面培训高素质的人员。对未来一代材料科学家的培训，特别是那些精通量子现象的科学家，对于未来材料研究的范式转变至关重要。 技术摘要：稀土基蜂窝晶格材料是一类非传统的量子磁体。由于存在强烈的量子波动自旋，结合强自旋轨道耦合产生的各向异性相互作用，这些材料可以拥有与传统（基于3d过渡金属）量子磁体不同的量子相。该项目将研究一系列在稀土基蜂窝晶格材料中发现的现象，包括量子二聚体磁性导致场诱导的玻色爱因斯坦凝聚，Ising类量子临界性，以及实现高度纠缠Kitaev量子自旋液体的有希望的途径。该项目涉及稀土蜂窝材料的批量样品的合成，特别强调单晶生长。这些材料的特点是热力学探针和非弹性中子散射。 热力学给出了相图的路线图，而非弹性中子散射使人们能够理解新兴的准粒子激发及其随外加磁场的演变。相对较弱的相互作用能的稀土材料，使使用一个强大的方法来确定这些材料中的相互作用参数，通过场极化非弹性中子散射谱的理论建模。这项工作与物理学研究的其他广泛领域有关，例如多孔介质中的超流氦，超导性和超冷原子气体。这项工作的影响也超出了多体量子物理学;通过这个项目，学生谁是代表性不足的少数群体的一部分，在物理，鼓励学生探索材料中磁性和相变的概念，并获得实践研究经验。材料研究部（DMR）的这项资助支持研究，以了解一系列已发现在罕见的材料中表现出来的现象。该奖项反映了NSF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。