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

San Diego State University Foundation, San Diego CA

Investigators

Abstract

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. ***