Microscopic investigation of quantum materials based on nuclear magnetic resonance

我们基础研究的科学目标是理解由量子力学驱动的固体的非直觉行为。我们智力追求的两大支柱是量子磁学和奇异超导。前者研究的是受挫的“自旋液体”中的磁矩，这些液体在绝对零度附近继续波动而不经历相变。本质上，这些磁铁的行为就好像它们不是磁铁一样。破译它们的神秘性质是当今量子材料研究的圣杯。后者寻求理解在某些种类的氧化铜和铁镍中电阻突然消失背后的机制。

The scientific goal of our fundamental research is to understand the non-intuitive behavior of solids driven by quantum mechanics. Two major pillars of our intellectual pursuit are quantum magnetism and exotic superconductivity. The former examines magnetic moments in frustrated “spin liquids” that continue fluctuating near absolute zero without undergoing a phase transition. In essence, these magnets behave as if they were not a magnet. Deciphering their mysterious properties is the holy grail of today's quantum materials research. The latter seeks understanding of the mechanisms behind sudden disappearance of electrical resistance in some classes of copper-oxides and iron-pnictides. NSERC Discovery Grant enables us to investigate these fundamental problems of physics based on a microscopic probe called Nuclear Magnetic Resonance (NMR) spectroscopy. NMR is the underlying principle behind the magnetic resonance imaging (MRI) used in hospitals. NMR is exceptional at gaining deep insight at microscopic levels into why electrons and atoms behave the way they do. We investigate quantum materials using NMR conducted in extreme environments, such as low temperatures near absolute zero, ultra high pressure, and/or high magnetic field. My students conduct in-house research in our phenomenally well-equipped cryogenic NMR laboratory. They have unlimited access to three sets of NMR spectrometers, three types of superconducting magnets which can generate high magnetic fields up to 16 Tesla, high pressure cells to reach 3 to 9 GPa, and top-loading helium-3 and dilution refrigerators with the base temperature as low as 0.35 K and 0.009 K, respectively. The total value of these infrastructure exceeds $2-million. Their operational cost is very high, but so are the rewards to my students and Canada. Our superb research capabilities allow my students to establish high caliber collaborations with the world's leading researchers and publish high profile papers. The broad array of equipment also helps my students develop problem solving skills through hands-on training on the electronics, designing, manufacturing, installation and maintenance of cryogenic gears, and computer interfacing of sophisticated electronics. The versatile nature of my student training at all levels from undergraduate to postdoctoral researchers leads to a wide variety of career opportunities for them. In the coming 5 years, I propose to extend our research operation both in terms of the group size and scope. We are venturing into a new exciting direction of research on frustrated magnetism in the pyrochlore lattice, while maintaining our strength in research on kagome spin liquids. We also plan to refocus our attention on investigations of copper- and iron-based high temperature superconductors in view of the recent developments in the research field.