Synthesis of Magnetic Cr-Based Chalcogenide Spinels: From Nanocrystals to Thin Films

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Professor Arunava Gupta of the University of Alabama is receiving an award from the Macromolecular, Supramolecular and Nanochemistry Program to investigate novel low temperature routes, involving solution chemistry and chemical vapor deposition methods, for the synthesis and characterization of a promising class of magnetic Cr-based chalcospinel materials. These materials, synthesized in the form of monodisperse nanocrystals and thin films, will be characterized using advanced analytical techniques and their physical properties studied in detail. The program is motivated by theoretical results obtained by the investigator that suggest the exciting possibility of inducing half-metallicity - i.e., a material in which there is a gap in one spin band at the Fermi level and no gap in the other spin band - in some of the mixed Cu,Cd chalcospinels. The intellectual merit of the research lies in the synthesis and investigation of the novel mixed chalcospinels utilizing innovative synthesis and characterization methods that have the potential for realizing a new class of spintronic materials. Guided by band structure calculations that will be conducted in parallel, the synthesis of other substituted chalcospinel systems will also be attempted. In collaboration with Oak Ridge National Laboratory, ultra high-resolution scanning transmission electron microscopy with atomic number contrast (STEM-Z) characterization technique will be utilized for detailed structural characterization of the nanocrystals and thin films. Project personnel will play a key 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, public tours and demonstrations. Professor Arunava Gupta of the University of Alabama is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry to investigate a class of complex sulfur and selenium-based inorganic materials - referred to as chalcospinels - that display novel magnetic properties. As part of the research, the PI and his students will utilize unique solution chemistry and vapor deposition approaches for the controlled synthesis of nanocrystals and thin films of these materials. Of particular interest are some mixed chalcospinels, which are theoretically predicted to belong to a small class of exotic materials called half-metals. Half-metallic materials are considered one of the "holy grails" of spin electronics research, and continue to be elusive. This research will help maintain and increase the momentum of the young field of spin electronics by realizing the potential of this extremely interesting class of materials that have thus far not been fully exploited. The project requires a multidisciplinary effort that will make significant contributions to scientific knowledge, education, outreach and infrastructure. Project personnel will play a key 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, public tours and demonstrations.