New magnetic materials are required for use in emerging electronic devices that exploit the spin of the electron in addition to its charge, commonly referred to as spintronics. In particular, magnetic materials that display semiconducting or insulating characteristics are highly desirable, but their choice is presently limited. Dr. Gupta of the University of Alabama is investigating a class of complex sulfur and selenium-based inorganic materials - referred to as chalcospinels - that display novel magnetic properties. He is particularly interested in the synthesis of new semiconducting and insulating chalcospinels in the form of very small "nanocrystals" using wet chemistry approaches. Unlike bulk synthesis, which usually requires high temperatures and extended reaction time, solution-based synthesis of nanoscale materials can be carried out at much lower temperatures and at a reduced time scale. However, directly probing the physical properties of individual nanocrystals is challenging because of a lack of suitable techniques. In addition to synthesis, Dr. Gupta actively works with United States and international collaborators to develop new microscopy-based characterization methods for probing the intrinsic magnetic and electrical properties of the nanocrystals. The project requires a multidisciplinary effort that makes significant contributions to scientific knowledge, education, outreach and infrastructure. Dr. Gupta also plays a role in several ongoing education and outreach activities related to the proposed research. These include collaboration with local schools to facilitate participation by high school students in research, as well as public tours and demonstrations.
In this research program, Dr. Arunava Gupta of the University of Alabama is supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program to investigate novel solution chemistry routes for the synthesis of a promising class of magnetic Cr-based chalcospinel materials in the form of nanocrystals. Motivation for these materials is derived from theoretical studies suggesting the possibility of realizing unique magnetic and electrical properties in some complex chalcospinels. These materials may additionally serve as important model systems for fundamental studies of the interaction between charge carriers and magnetic ions. Guided by band structure calculations that are conducted in parallel, nanocrystal synthesis of a family of substituted chalcospinels are being explored. A potential limitation of nanocrystals as compared to bulk is the lack of appropriate methods for directly measuring the nanoscale properties. Therefore, the project also utilizes novel electron spectroscopic imaging techniques to probe the intrinsic physical properties of the nanocrystals. Dr. Gupta is an active participant in the multi-disciplinary Center for Materials for Information Technology (MINT) at the University of Alabama and leverages the considerable resources available through MINT for the maximum impact of outreach and dissemination of results specifically related to this work. Dr. Gupta also plays a key role in several on-going education and outreach activities related to the proposed research. These include collaboration with local schools to facilitate participation by high school students in research, public tours, and demonstrations.