CAREER: Investigations of Novel Low Temperature Behavior in Materials

9701548 Schiffer这是一份关于磁性材料的职业建议，从计算机光盘到汽车发动机，磁性材料被应用于现代技术的各个方面。在这些材料中，磁矩（可以被认为是微观的量子力学棒状磁体）相互作用，相互作用的性质对材料性能有深远的影响。提出的研究将调查两类磁性材料：几何挫折磁铁，其中磁矩的几何位置导致相互作用之间的精确平衡竞争；巨大的磁阻锰矿，其中磁矩之间的相互作用与电流的传导密切相关。提出的教育倡议将是现代凝聚态物理研讨会课程的发展。由于标准的凝聚态物理课程通常不涵盖过去三十年的发展，本课程将使学生对当前感兴趣的研究领域有一个广泛的概述。拟议的CAREER研究将研究新型磁性材料在低温下的性能。研究的一个主题将是几何上的挫折磁体，其中磁性离子以反铁磁性相互作用，但相互作用受到晶格几何的挫折。这些系统的热力学测量计划作为磁场，温度和非磁性杂质浓度的函数，以阐明其新的低温行为。第二个研究领域将是对最近显示出大磁阻的稀土锰矿石的调查。特别地，这些材料的组成相图将被检查，以了解观察到的各种磁相和电子相之间的转变。并计划开设现代凝聚态物理新课程。本课程的目的是让研究生和高级本科生接触到现代研究课题（如自旋玻璃、液氦和高温超导体），这些课题通常被排除在凝聚态物理的标准课程之外。＊＊＊

9701548 Schiffer This is a CAREER proposal on magnetic materials that are employed in all facets of modern technology from computer discs to automobile engines. In these materials, the magnetic moments (which can be thought of as microscopic quantum mechanical bar magnets) interact with each other, and the nature of the interactions has a profound impact on the material properties. The proposed research will investigate two classes of magnetic materials: geometrically frustrated magnets in which the geometrical placement of the magnetic moments results in a precisely balanced competition between interactions and colossal magnetoresistance manganites in which the interaction between the magnetic moments is closely tied the conduction of electrical current. The proposed educational initiative will be the development of a seminar course in modern condensed matter physics. Since standard condensed matter physics courses typically do not cover the developments of the past three decades, this course will give students a broad overview of research areas of current interest. %%% The proposed CAREER research will investigate the properties of novel magnetic materials at low temperatures. One subject of research will be geometrically frustrated magnets, in which the magnetic ions interact antiferromagnetically, but the interactions are frustrated by the lattice geometry. Thermodynamic measurements on these systems are planned as a function of magnetic field, temperature, and non-magnetic impurity concentration in order to elucidate their novel low temperature behavior. A second area of research will be investigations of the rare-earth manganites which have been recently shown to display large magnetoresistance. In particular the compositional phase diagrams of these materials will be examined to understand the observed transitions between various magnetic and electronic phases. The development of a new course in modern condensed matter physics is also planned. The intent of the course is to expose graduate students and advanced undergraduates to modern research topics (such as spin glasses, liquid helium, and high temperature superconductors) which are typically excluded from standard courses on condensed matter physics. ***