Nanoscale Quantum Sensing of Magnetic and Noncentrosymmetric Weyl Semimetals

Non-Technical Abstract: Harnessing quantum materials for cutting-edge scientific research and technological innovations constitutes a key mission of the ongoing quantum revolution. Magnetic Weyl semimetals, a group of scientifically intriguing and technologically important materials, are naturally relevant in this context thanks to their promise for delivering advanced functionalities such as high density, ultrafast processing speeds and improved stability to next-generation quantum electronics applications. In this project, the principal investigator plans to introduce scanning-probe quantum microscopy to investigate the underlying correlation between microscopic magnetic phases and topological properties of emergent Weyl semimetals. An important goal here is to leverage quantum spin sensors to reveal the interplay between topology, magnetism, and valley transport behaviors in topological quantum magnets. In parallel with the proposed research, this project also dedicates a major effort to increasing society’s awareness of some of the most exciting developments and challenges in condensed matter physics, materials science and quantum sciences and technologies. It promotes the participation of young researchers at the forefront of interdisciplinary scientific research. Outreach activities include lectures, learning and demo materials for nearby technical colleges and high schools, so that contemporary scientific knowledge can reach out to a broad audience. Technical Abstract: Recently, magnetic Weyl semimetals have received immense interest in cutting-edge condensed matter physics research. Tremendous efforts have been devoted to investigating exotic topological behaviors in this new family of quantum materials. Examples include Weyl fermion mediated ferromagnetism, chiral magnetic effect, magnetic vortices, quantum anomalous Hall effect and many others. Here the principal investigator proposes utilizing quantum spin sensors to perform nanoscale quantum sensing of novel magnetic and noncentrosymmetric Weyl semimetals RAlSi (R = rare earth element). Exploiting the highly competitive spatial and field sensitivity of scanning-probe quantum microscopy, this project aims to visualize the exotic spin density waves and to probe valley transport properties in NdAlSi, uncovering the underlying mechanism of Weyl mediated unconventional magnetism. Taking advantage of the dipole-dipole coupling between quantum spin sensors and Weyl materials, the research team further proposes to achieve local excitation, control, and detection of axial electromagnetic field-driven chiral anomaly in CeAlSi, opening new pathways to explore microscopic quantum spin and charge behaviors in topological materials. This project makes important contributions to the burgeoning field of quantum materials and promotes the role of Weyl semimetals in developing innovative quantum microelectronic devices for next-generation information technologies. By developing scanning-probe quantum sensing techniques and demonstrating their operation over a broad range of conditions, it also brings new experimental approaches to study topological physics in emergent quantum states of matter. 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.