Spin fluctuations in itinerant electron systems

非技术摘要：虽然这是一个百年前的问题，但人们对磁学仍然知之甚少。在两种极端的磁态中--磁矩集中在小空间体积(局部磁矩)和被整个化合物共享的磁态(巡回磁矩)，前者在理论上仍然被描述得更好，大多数真实的材料实际上位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铁。人们特别感兴趣的是，当温度降低到接近绝对零度时，或者向量子相变(QPT)方向下降时会发生什么，与更常见的相变，例如液体到固体的相变相比，量子相变从根本上是截然不同的。奇异的物理被认为是从QPTs中出现的，这些将通过调节参数来研究，如成分、压力或磁场。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将开发一个关于科学陈述技能的课程，并将为儿童和成人建立两个系列的实验室开放参观。技术摘要：这个NSF奖支持凝聚态物理的实验研究和教育，重点是在巡回瞬间状态下物质的新磁性状态。特别是，这项提议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个已知此类磁性系统的化学可调性，以设计感兴趣的新化合物。该项目的主要任务是研究(I)巡回电子磁铁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)巡回磁铁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，并优化材料以用于医疗和可能的新技术应用。PI将开设一个关于科学演示技能的课程，并将建立两个系列的实验室开放参观，为儿童和成人提供实践体验。

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.