CAREER: Understanding and Controlling the Integration of Magnetism into Semiconducting Mixed Metal Chalcogenides

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TECHNICAL SUMMARY:The ability to develop in a single material, ferromagnetic and semiconducting functionalities which are desirable for spintronics as well as thermoelectric devices is a great challenge in solid state chemistry. This CAREER grant supported by the Solid State and Materials Chemistry (SSMC) program seeks to exploit the marked structural features of synthetic and naturally occurring ternary and quaternary heavy main-group metal chalcogenides with general composition Pb(n+2)Sb2(m+1)Q(n+3m+5 and MtPb(n-t+2)Sb2(m+1)Q(n+3m+5) (M = Mn, Fe, Co; Q = S, Se, Te) to: (i) investigate the stability of the framework structure upon changing the nature of transition metal elements and/or the nature of chalcogen atom; (ii) investigate how the magnetism and the charge transport properties of this family of compounds change with modification of the composition and structure; and (iii) understand the correlation between the charge carrier's concentration and mobility and the coupling between magnetic centers in the structure. This will be done by combining two approaches: (a) the nature and stoichiometry of elements within a given structure type will be systematically varied and their effects on the magnetism and electronic transport of the resulting materials will be assessed, (b) for a given system, phases with structures closely related to each other (pseudo-homologous series) will be used to investigate the effects of structural evolution (changes in structure type within the homologous series) on the magnetism and charge transport properties of the materials. NON-TECHNICAL SUMMARY:This research program aims to develop ferromagnetic and semiconducting functionalities in a single material. The availability of such materials could impact the architecture of modern computers where an entire computer is built on a single semiconducting chip using a device capable of electronically writing and reading information to and from a magnetic material. Additionally, the materials can also be used to build a device capable of cooling the whole computing system. The multi-component educational program proposed in this CAREER grant will provide research and teaching experiences to K-12 teachers, high school students, undergraduate students, graduate students and postdoctoral associates. Graduate students and postdoctoral researchers will receive outstanding training on state-of-the-art techniques in high temperature solid-state synthesis, X-ray diffraction and physical properties measurements. They will also be involved in data analysis as well as preparation of manuscripts for publication. Although, the University of New Orleans (UNO) is located in an "urban city" with about 58% of the population from African American origin, the number of high school seniors from this group entering higher education is still low. The proposed Community Services and Learning Experiences for Chemistry Freshmen program will provide hands-on experience and training to current UNO Chemistry freshmen while simultaneously stimulating interest among high school students (sophomores, juniors and seniors) in chemistry.