LEAPS-MPS: Unveiling the Interplay of Chiral Transport, Magnetism, and Topology in Weyl Magnets: A Magneto-Optical Investigation

在固体中，电子表现出许多行为，取决于它们的晶体结构和组成元素。对于半导体，电子的重或轻取决于掺杂元素。无质量的电子驻留在石墨烯上，石墨烯是一种原子薄的碳蜂窝晶格。最近，在一类名为Weyl半金属的新材料中发现了一种新的电子行为。新电子是无质量的，它们的自旋被锁定在它们运动的方向上。特别是，电子具有手性或手性，决定了电子是向前还是向后移动。这种手性电子为新的高速电子学提供了潜力。这项LEAPS-MPS项目研究了块状材料的磁化如何通过调制左手和右手之间的光偏振来影响手性电子行为。该项目旨在通过为德克萨斯州南部平原的年轻学生提供光学和偏振测量方面的实践研究经验，提高对基础材料科学的认识和理解。该项目的每月公众宣传演示将吸引和激励下一代科学家和研究人员，特别是K-12学生，让父母参与他们孩子的教育，并为服务不足的学生群体创造一个支持他们从事科学和研究的环境。此外，该项目还加强了希望攻读凝聚态物理高级学位课程的初三和高年级本科生的物理课程。技术和手性费米子是在三维动量空间的费米能级上具有两个非简并带交叉的材料中出现的准粒子-称为Weyl点。Weyl点作为动量空间中磁场的单极子和反单极子，产生了费米弧表面态、手征反常和本征反常霍尔电导等奇特性质。磁性Weyl半金属的发现引起了人们对手性费米子与磁性之间关系的极大兴趣。然而，磁性织构和拓扑Weyl性质之间复杂的相互作用还没有完全被理解。LEAPS-MPS奖支持利用先进的磁光技术进行实验研究，以研究磁性Weyl半金属中手性输运、磁性织构和拓扑之间的复杂关系。提出的利用非线性手征抽运和宽带红外霍尔探测的时间分辨磁光测量方法可以同时检测磁性Weyl半金属中的非平衡手性态、局域磁织构动力学和本征反常霍尔电导。该项目提供了通过光、电和磁手段控制拓扑功能的新见解，为研究Weyl半金属的电子结构及其在非耗散信息控制中的潜在应用奠定了基础。该奖项反映了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 SUMMARYIn a solid, electrons exhibit many behaviors depending on their crystal structure and constituent elements. For semiconductors, electrons are heavy or light depending on a doping element. Massless electrons reside on graphene, an atomically thin honeycomb lattice of carbon. Recently, a new type of electron behavior has been discovered in a new class of materials called Weyl semimetals. The new electrons are massless, and their spin is locked in the direction of their motion. Particularly, the electrons have handedness or chirality, determining whether the electrons move forward or backward. Such chiral electrons offer the potential for new and high-speed electronics. This LEAPS-MPS project studies how the magnetization of bulk materials can affect chiral electron behavior measured by modulating the light polarization between left-handed and right-handed. This project aims to increase awareness and understanding of basic material science through hands-on research experience in optics and polarimetry for young students in the South Plains of West Texas. The monthly public outreach demonstrations in this project will engage and inspire the next generation of scientists and researchers, particularly K-12 students, by involving parents in their children’s education and creating a supportive environment for under-served student populations to pursue science and research. In addition, this project strengthens the physics curriculum for junior and senior undergraduate students who want to pursue advanced-degree programs in condensed matter physics.TECHNICAL SUMMARYChiral fermions are quasiparticles that arise in materials with two non-degenerate bands crossing – called Weyl points – at the Fermi level in three-dimensional momentum space. Weyl points, acting as monopoles and anti-monopoles of the magnetic field in momentum space, give rise to exotic properties such as Fermi arc surface states, the chiral anomaly, and the intrinsic anomalous Hall conductivity. The discovery of magnetic Weyl semimetals has generated considerable interest in the relationship between chiral fermions and magnetism. However, the complex interplay between magnetic texture and topological Weyl properties is not fully understood. This LEAPS-MPS award supports experimental research utilizing advanced magneto-optical techniques to investigate the intricate relationship between chiral transport, magnetic texture, and topology in magnetic Weyl semimetals. The proposed time-resolved magneto-optical measurement using nonlinear chiral pumping and broadband infrared Hall probing enables the simultaneous examination of non-equilibrium chiral states, local magnetic texture dynamics, and intrinsic anomalous Hall conductivity in magnetic Weyl semimetals. This project provides new insights into controlling topological functionalities through optical, electrical, and magnetic means, providing a foundation for investigating Weyl semimetals’ electronic structure and their potential applications in non-dissipative information control.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.