CAREER: Low-Dimensional Spin Systems: Interplay of Chemical Pressure on Triangular Lattices with Spin- and Orbital Degrees of Freedom

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TECHNICAL SUMMARY:The objective of this CAREER proposal, supported by the Solid State and Materials Chemistry (SSMC) program, is to understand the effects of chemical pressure on geometrically frustrated lattices in the presence of spin and orbital degrees of freedom. A recently identified and subsequently synthesized new series of compounds exhibiting a triangular lattice of magnetic ions confined in a robust two-dimensional building block has emerged as a suitable template to investigate: (1) the impact of induced slight structural distortions and (2) the dependence of the magnetic correlations on the respective spin system. A unique opportunity to derive insights into tuning ferromagnetic and anti-ferromagnetic correlations mediated through super-exchange pathways has emerged for this series of compounds. The investigations are mainly experimental and encompass solid state chemistry synthesis, spectroscopy, magnetization, and specific heat measurements. The scientific impact of this work will contribute to a fundamental understanding of phenomena occurring on geometrically frustrated systems, including aspects of spin-orbit coupling for divalent and trivalent 3d transition metal cations. Furthermore, the discovery of new members of the highly unique class of ferromagnetic insulators represents an additional exciting advance and an important contribution to the field of multifunctional materials. NON-TECHNICAL SUMMARY:Advances in the field of next-generation materials with relevance to energy and sensors rely on the development of a fundamental understanding of the properties of materials. Further, the design of new classes of materials and the ability to control important functional parameters of these materials require a detailed understanding of the mechanisms at work. To this end, the conceptual framework underlying the proposed research activities, supported by the Solid State and Materials Chemistry program (SSMC), seeks to establish the fundamental structure-property relationships that define the behavior and utility of new classes of functional materials. For example, recent discoveries in our laboratory demonstrate our ability to tune the magnetic properties of a novel series of insulators; these materials should ultimately find use as magnetoresistive sensors for global positioning/navigation in remote areas. In conjunction with these activities, the proposed educational activities seek to provide training in the interdisciplinary areas of solid state chemistry and condensed matter physics for both undergraduate and graduate students at the University of Houston, which is ranked second among the country's most diverse universities. The PI has established mentoring and volunteer programs from elementary to K-12 levels at schools within the Houston Independent School District. These programs communicate fundamental materials science geared toward understanding scientific aspects of everyday life in experiments and lectures to raise awareness and fascination for next-generation challenges. Furthermore, the PI's activities aim to promote materials science, encompass interaction with young scientists at large, and include international collaborations with highly regarded institutions.