Weyl Semimetals in Extreme Magnetic Fields

非技术摘要材料系统物理学的最新进展，通常被称为“凝聚态物质”，揭示了被称为拓扑性质的新类型的特征。具有某些类型的拓扑性质的材料可以用于制造量子信息技术的器件。在这项提案中，研究小组将研究某些被称为狄拉克和韦尔半金属的材料，这些材料表现出非常有趣的拓扑性质。这些材料的合成非常具有挑战性，但该团队拥有生产它们的独特专业知识，这些材料将被提供给世界各地致力于推进量子技术的其他研究小组。在这项提案中，合成的材料将通过将它们置于磁场、应变和各种化学物质中进行研究。它们的性质将通过先进的技术来确定，如电传输、光谱分析和热传输测量。其目标是发现如何定制这些材料的拓扑性质的新知识，以便它们可以用于制造量子技术的设备。该项目还包括一项计划，即推出一本关于量子材料的基于图像的书，以告知公众。这项研究将招收来自代表性不足群体的研究生和本科生，以扩大对这一研究领域的参与。技术摘要提出了三个主要项目，将研究对称破缺磁场的想法扩展到应用磁场之外。受最近关于非均匀应变可以作为有效磁场的预测的启发，第一个项目研究了单轴应变场对磁性和非磁性Weyl材料中磁输运现象的影响。第二个项目探索了当拓扑表面态的对称性保护受到损害时，它们的稳健性问题。在这种情况下，PI将研究仅仅接近拓扑非平凡相是否足以允许拓扑态的问题。在第三个项目中，PI通过研究可以驱动或抑制拓扑态的竞争相互作用进一步扩展了这一概念，特别是关注了近藤晶格材料中拓扑和浮现自由度是如何传输电荷和熵的。这些项目拓宽了这项研究提案的原始概念，解决了该领域最有趣的问题之一-对称破缺及其关联是如何与电子拓扑交织在一起的？该项目包括一项推出一本基于图像的量子材料书的计划，展示了最近的技术进步，使人们能够可视化固体的量子本质。来自不同背景的学生将被招募参加计划中的研究项目。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical AbstractRecent advances in the physics of material systems, often called “condensed matter” have revealed new kinds of characteristics called topological properties. Materials with certain types of topological properties can be used in manufacturing devices for quantum information technology. In this proposal, the team will investigate certain materials called Dirac and Weyl semimetals which exhibit very interesting topological properties. These materials are very challenging to synthesize, but the team has unique expertise to produce them and these will be supplied to other research groups around the world who are working to advance quantum technology. In this proposal, the materials synthesized will be studied by subjecting them to magnetic fields, to strain, and to various chemicals. Their properties will be determined through advanced techniques such as electrical transport, spectroscopy, and thermal transport measurements. The goal is to uncover new knowledge of how to tailor the topological properties of these materials so that they can be used in making devices for quantum technology. The project also includes a plan to launch an image-based book on Quantum Materials to inform the public. Graduate and undergraduate students from underrepresented groups will be recruited in this research to widen participation in this research area.Technical AbstractThree main projects are proposed that extend the idea of studying symmetry breaking fields beyond applied magnetic fields. Inspired by recent predictions that inhomogeneous strain can act as an effective magnetic field, the first project studies the effect of uni-axial strain fields on magneto-transport phenomena, in both magnetic and non-magnetic Weyl materials. The second project explores the question of the robustness of topological surface states when their protection by symmetry is compromised. In this case, the PI will study the question whether the mere proximity to a topologically non-trivial phase is sufficient to allow topological states. In the third project, the PI extends this idea further by studying competing interactions which can drive or suppress topological states, focusing in particular on how topological and emergent degrees of freedom transport charge and entropy in Kondo-lattice materials. These projects broaden the original conception of this research proposal, attacking one of the most interesting questions in the field - how is broken symmetry, and its associated correlations, intertwined with electronic topology? The project includes a plan to launch an image-based book on Quantum Materials, showcasing the recent technological advances that have allowed the visualization of the quantum nature of solids. Students from different backgrounds will be recruited to participate in the planned research project.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.