Microscopic Investigation of Quantum Materials

我研究的主要重点是理解固体的非直观量子行为。我们专注于低温NMR（核磁共振），并对具有基本科学兴趣和长期技术创新潜力的各种量子材料进行微观研究，例如铁基高温超导体，自旋液体，稀磁半导体（DMS）和石墨烯。NMR擅长深入了解电子在微观水平上的行为方式。因此，我们所有项目的首要主题都是回答：“它是如何发生的？“例如，铁-磷属元素化物可以在低于55 K的温度下超导而没有电阻;电子如何形成具有单线态自旋的超导库珀对，即使铁是具有平行自旋的铁磁体？DMS在~100 K以上表现出铁磁行为，具有自旋电子学应用的前景;在如此大的能量尺度下，半导体中的稀磁矩是如何相互作用的？为了解决这些可能对技术产生重大影响的基于好奇心的问题，我们在我设备精良的低温NMR实验室进行了内部研究。我的学生可以无限制地使用我们的牛津顶部加载稀释冰箱（基础温度9 mK），Janis顶部加载氦-3低温恒温器（基础温度350 mK），三种类型的超导磁体（高达16特斯拉）和三台NMR光谱仪，并与世界一流的合作者一起推动我们备受瞩目的研究项目。因此，我的实验室通过设计，制造，计算机接口和维护我们的设备，为学生提供科学研究培训和解决问题的技能，为他们未来的就业。在未来的5年里，我计划通过扩展到新的和令人兴奋的研究方向，如DMS和石墨烯，同时保持我们在非常规超导和量子磁性方面的国际地位，来扩大我们的研究规模和范围。

The main focus of my research is in understanding the non-intuitive quantum behavior of solids. We specialize in cryogenic NMR (Nuclear Magnetic Resonance), and conduct microscopic investigations of a wide range of quantum materials with basic scientific interests as well as long-term potential for technological innovations, e.g. iron-based high temperature superconductors, spin-liquids, dilute magnetic semiconductors (DMS), and graphene. NMR is good at gaining deep insight into why electrons behave the way they do at microscopic levels. The overarching theme that encompasses all of our projects is therefore in answering: "How does it happen?" For example, iron-pnictides can superconduct without electrical resistance below 55 K; how can electrons form superconducting Cooper pairs with singlet spins, even though iron is a ferromagnet with parallel spins? DMS exhibit ferromagnetic behavior above ~100 K, with the prospect for spintronics applications in the future; how do dilute magnetic moments interact with each other in semiconductors with such large energy scales? To address these curiosity-based questions with the potential for major impacts on technologies, we conduct in-house research in my exceptionally well-equipped cryogenic NMR laboratory. My students have unlimited access to our Oxford top-loading dilution refrigerator (base temperature 9 mK), Janis top-loading helium-3 cryostat (base temperature 350 mK), three types of superconducting magnets (up to 16 Tesla), and three NMR spectrometers, and drive our high-profile research projects with world-class collaborators. My laboratory thus provides students with scientific research training and versatile problem solving skills for their future employments through the designing, manufacturing, computer interfacing and maintenance of our equipment. In the coming 5 years, I plan to extend our research operation both in terms of the group size and scope, by expanding into new and exciting directions of research such as DMS and graphene, while maintaining our international presence in unconventional superconductivity and quantum magnetism.