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

最近在轻掺杂六硼化物A1-xLaxB6 （A = Ca, Sr，或Ba）中发现的高tc弱铁磁性（WF），刺激了理论和实验努力来理解这一现象。虽然已经提出了几个模型，但一个解释仍然难以捉摸。为了更好地了解WF的来源，将在2 K - 1100 K之间对受控样品进行电子顺磁共振（EPR）、单轴应力、微波吸收和磁化强度(M)的测量。此外，系统称为多铁性，MF，将进行研究。它们同时具有铁电性（FE）和铁磁性（FM）。有人认为BiMnO3是MF。BiMnO3的实验数据不完整。它的磁性、电学和结构性能将通过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相互作用的性质，并刺激这些化合物的未来工作。几个本科生和硕士生将参与这个项目。他们将接受尖端研究技术的培训，这为学生攻读博士学位或从事工业工作提供了良好的准备。最近在掺杂的CaB6中发现了铁磁性，这是现代磁学研究中最大的惊喜之一，对此仍然没有任何解释。选定的实验将进行，以提供新的见解，这些系统的物理，这可能导致正确的理论模型。同时，还将进行铁电性（FE）和铁磁性（FM）化合物的研究。尽管在这些系统中进行的工作很少，但可以想象许多重要的新应用。例子是多状态记忆元件，电场控制的调频共振装置，和可变传感器。几个本科生和硕士生将参与这个项目。他们将接受尖端研究技术的培训。这些课程为攻读博士学位或从事工业工作提供了极好的准备。高中学生和教师也将参加这个项目。为了提高K-12的科学教育质量，PI小组成功地开展了外展计划，这将继续下去

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.***