A Study of the Magnetic Properties of Some Strongly Correlated Electron Systems

最近在轻掺杂六硼化物A1-xLaxB 6（A = Ca，Sr，或Ba）中发现的高Tc弱铁磁性（WF）激发了人们对这一现象的理论和实验研究。 虽然已经提出了几种模型，但解释仍然难以捉摸。 为了更好地了解WF的起源，将在2 K - 1100 K之间通过电子顺磁共振EPR、单轴应力、微波吸收和磁化强度M对受控样品进行测量。此外，系统称为多铁性，MF，将进行研究。 它们同时是铁电体（FE）和铁磁体（FM）。有人认为BiMnO_3是MF。关于BiMnO_3的实验数据是不完整的。 它的磁性，电学和结构特性将通过EPR，M，比热，拉曼，X射线和电极化来测量。 这项工作应该有助于了解目前的相互作用的性质，并刺激未来的工作在这些化合物。 一些本科生和硕士生将参与这个计划。 他们将接受尖端研究技术的培训，为学生获得博士学位做好准备。计划或在行业的职业生涯。最近在掺杂的CaB 6中发现的铁磁性是现代磁性研究中最令人惊讶的发现之一，对此仍然没有解释。将进行选定的实验，以提供对这些系统的物理学的新见解，这可能导致正确的理论模型。 此外，同时铁电，FE和铁磁，FM的化合物的研究将进行。尽管在这些系统中进行的工作很少，但可以想象出一些重要的新应用。 实例是多状态存储器元件、电场控制FM谐振装置和可变换能器。 一些本科生和硕士生将参与这个计划。 他们将接受尖端研究技术的培训。 这些都为博士学位提供了很好的准备。计划或在行业的职业生涯。 高中学生和教师也将参加这个项目。 这将继续由PI的小组进行成功的推广计划，以提高K-12的科学教育质量。

The recent discovery of high-Tc weak ferromagnetism, WF, in lightly doped hexaborides, A1-xLaxB6 (A = Ca, Sr, or Ba), has stimulated theoretical and experimental efforts to understand the this phenomenon. While several models have been proposed, an explanation is still elusive. In order to gain a better understanding of the origin of the WF, measurements by Electron Paramagnetic Resonance, EPR, uniaxial stress, microwave-absorption, and magnetization, M, in controlled samples will be conducted between 2 K - 1100 K. Also, systems known as multiferroics, MF, will be studied. They are simultaneously ferroelectric, FE, and ferromagnetic, FM. It has been suggested that BiMnO3 is MF. The experimental data on BiMnO3 is incomplete. Its magnetic, electrical and structural properties will be measured by EPR, M, specific heat, Raman, X-rays, and electric polarization. This work should help understand the nature of the interactions present and stimulate future work in these compounds. Several undergraduates and master's students will be involved in this program. They will be trained in cutting-edge research techniques, which provided the students excellent preparation for Ph.D. programs or for careers in industry. %%%The recent discovery of ferromagnetism in doped CaB6 is one of the great surprises in the modern study of magnetism for which there is still no explanation. Selected experiments will be carried out to provide new insight into the physics of these systems, which could lead to the correct theoretical model. Also, studies of compounds that are simultaneously ferroelectric, FE, and ferromagnetic, FM, will be carried out. Despite little work having been performed in these systems, a number of important new applications can be imagined. Examples are multiple state memory elements, electric field controlled FM resonance devices, and variable transducers. Several undergraduates and master's students will be involved in this program. They will be trained in cutting-edge research techniques. These provide excellent preparation for Ph.D. programs or for careers in industry. High school students and teachers will also participate in this program. This will continue the successful outreach program conducted by the PI's group in order to improve the quality of science education in K-12.***