Spin fluctuations in itinerant electron systems

非技术性摘要：虽然磁性是一个世纪的老问题，但人们对它的了解仍然很少。在两种极端的磁性状态中--磁矩局限于小空间体积的状态（局部磁矩）和整个化合物共享的状态（巡回磁矩），前者在理论上仍能得到更好的描述，大多数真实的材料实际上处于两者之间的连续体中。该项目的主要目标是发现和表征没有磁性元件的新型巡回磁体。特别感兴趣的是理解当温度降低到接近绝对零度或朝向量子相变（QPT）时会发生什么，与更熟悉的相变（例如液体到固体）相比，量子相变（QPT）是根本不同的转变。奇异物理学被认为是从QPT中出现的，这些将通过调整参数（如成分，压力或磁场）进行研究。参与该项目的本科生和研究生将接受晶体生长和表征方面的培训，这是材料驱动凝聚态研究的宝贵工具。PI将开设一个科学演示技能课程，并将建立两个系列的实验室开放日，为儿童和成人提供实践经验。技术摘要：该奖项支持凝聚态物理学的实验研究和教育，重点关注巡游矩体系中物质的新磁态。特别是，该提案的目标是研究不含磁性元素的新型巡回磁体，其中将探索仅有的三种已知的此类磁性系统的化学可调谐性，以设计感兴趣的新化合物。该项目的主要目标是研究（i）巡回电子磁体的结构和物理性质之间的相关性，（ii）电子和磁基态之间的相互作用，以及（iii）巡回磁体系统中的非费米液体行为。此外，还将研究最近发现的一些相关合金的硬度，并对这些材料进行优化，以用于医疗和可能的新技术应用。PI将开发一个关于科学演示技巧的课程，并将建立两个系列的实验室开放日，为儿童和成人提供实践经验。

NON-TECHNICAL ABSTRACT: While a century old problem, magnetism remains poorly understood. Of the two extreme magnetic states - those with magnetic moments localized in small spatial volumes (local moments) and those shared by the entire compound (itinerant moments), the former remains better described theoretically, with most real materials actually residing in the continuum between the two. The main goal of this project is to discover and characterize novel itinerant magnets without magnetic elements. It is of particular interest to understand what happens as the temperature is lowered close to absolute zero, or towards quantum phase transitions (QPT), fundamentally distinct transitions compared to the more familiar phase transitions, for example liquid-to-solid. Exotic physics is believed to emerge from QPTs and these will be studied with tuning parameters such as composition, pressure or magnetic field. Undergraduate and graduate students involved in the project will be trained in crystal growth and characterization, valuable tools for materials driven condensed matter research. The PI will develop a class on scientific presentation skills, and will establish two series of lab open houses, for hands-on experience for children and for adults.TECHNICAL ABSTRACT: This NSF award supports experimental investigations and education in condensed matter physics, with focus on novel magnetic states of matter in the itinerant moment regime. In particular, the goal of this proposal is to investigate novel itinerant magnets containing no magnetic elements, where the the chemical tunability of the only three known such magnetic systems will be explored towards designing the new compounds of interest. The main thrusts of the project are studies of (i) the correlations between the structural and physical properties of itinerant electron magnets, (ii) the interplay between electronic and magnetic ground states and (iii) non-Fermi liquid behavior in itinerant magnet systems. In addition, the recently discovered hardness of some related alloys will be investigated and the materials optimized for medical and possibly new technological applications. The PI will develop a class on scientific presentation skills, and will establish two series of lab open houses, for hands-on experience for children and for adults.