RUI: Novel Heavy Element Transition Metal Oxides; Low Dimensional Magnetism vs. Geometric Magnetic Frustration

California State University-Long Beach Foundation, Long Beach CA

Investigators

Abstract

NON-TECHNICAL SUMMARY: Magnetic materials have been the subjects of scholarly research for many years. This project will focus on the investigation of a particular class of magnetic systems having triangular arrangements of magnetic ions, which display unusual and little-investigated behavior. The proposed parent materials will also be subjected to chemical modification, and the resulting systems will provide a great opportunity to elucidate the role of crystal symmetry and quantum aspects on determination of the resultant magnetism. A major focus will also be devoted to synthesis of magnetic materials and study of the effects of geometrical and low-dimensional structural contributions. Some of these systems are particularly important as they are expected to exhibit interesting electronic transport properties. The interdisciplinary nature of the project is attractive from an educational perspective for many scientific communities, i.e. chemistry, physics, electronics, materials, etc. Undergraduate and graduate students will be exposed to a large variety of synthetic methods, characterization techniques, and physical properties measurements in the field of solid-state materials chemistry. Some of the research will be conducted in national laboratories, offering valuable opportunities for students to collaborate with other scientists and benefit from hands-on research experience in world-class research facilities. Also, magnetism and magnetic materials are at the basis of many components of daily human life (electric motors, data storage devices, medical imaging technologies, etc.) and this project will advance public awareness of the field of magnetic materials. It will also include development of new courses and programs, attracting students to pursue academic studies in STEM fields, organizing outreach programs in local high schools, and presenting results at scientific conferences. TECHNICAL SUMMARY: In antiferromagnetic (AFM) materials with triangular arrangements of magnetic ions, all the spin constraints cannot be satisfied simultaneously and conventional static magnetic ordering is inhibited. This results in a phenomenon, which is known as geometric magnetic frustration (GMF) where exotic ground states with enormous degeneracies are present. Nonetheless, this condition may be violated when the exchange interactions of different strengths lift the degeneracy and the dominating interaction results in low dimensional magnetism (LDM). This project aims to develop a profound insight into both structural and electronic variables that determine the criteria for the two above-mentioned regimes, LDM vs. GFM. The goals will be achieved by exploratory syntheses, characterizations, and physical properties measurements of rationally designed materials. These will include novel 4d and 5d transition metal oxides in ordered NaCl structure type or in B-site ordered double perovskite structure type, which are composed of triangular magnetic sub-structure. Moreover, the successfully synthesized and characterized parent compounds will undergo further systematic chemical modifications, by which the oxidation states of magnetic ions and/or structural features will be altered. This in turn, will change the degree of frustration and will enable understanding of the interplay between the variables and the ground state magnetic structure. An essential component of the program is the high level of undergraduate and M.S.-level graduate students' participation, particularly those from underrepresented groups, in the societally important area of materials science.