nirt: Synthesis of and Structure-Function Relationships in Heterostructures of Quasi-2D Materials

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

This research applies a novel synthetic approach based upon modulated elemental reactants to kinetically trap oriented thin films of novel compounds, heterostructures, and superlattices based upon quasi-two-dimensional transition metal dichalcogenide compounds their 3d transition metal intercalates and phosphochalcogenide compounds. These materials provide unprecedented variability in the type of heterostructures that can be formed since the constituent materials range from wide and narrow gap semiconductors to antiferromagnetic insulators to semimetals to metals, some ferromagnetic, antiferromagnetic, or superconducting. X-ray diffraction, cross sectional TEM, SEM, AFM and STM will be used to characterize the structure and defects in these new materials. The targeted materials are expected to exhibit distinct and interesting magnetic and transport properties. Specific goals include: (1) grow and characterize metal-semimetal and metal-semiconductor superlattices; (2) produce unusual magnetic structures by preparing superlattices containing components with different magnetic structures and; (3) induce an insulator to metal transition in the correlated insulating MPX3 compounds by alloying and/or layering to produce quasi-2D correlated metallic states that we expect to have interesting conducting properties. Students will be trained in cutting-edge research techniques during this research and exposed to the challenges and rewards of industrial research through Oregon's Ph.D. internship program %%% This work uses a recently developed synthetic approach to prepare thin films of novel compounds, heterostructures, and superlattices based upon quasi-two-dimensional transition metal dichalcogenide compounds, their 3d transition metal intercalates and phosphochalcogenide compounds. These materials provide unprecedented variability in the type of heterostructures that can be formed since the constituent materials range from wide and narrow gap semiconductors to antiferromagnetic insulators to semimetals to metals, some ferromagnetic, antiferromagnetic, or superconducting. X-ray diffraction will be used to follow the evolution of the initial reactants to crystalline superlattices, to determine the superlattice modulation and to solve crystal structures of these new materials. Cross sectional TEM will be used to explore the nature and density of the stacking defects, and SEM, AFM and STM will be used to characterize their lateral structure. The targeted materials include metal-semimetal and metal-semiconductor superlattices, unusual magnetic superlattices, and correlated-electron conductors. These materials are expected to exhibit distinct, interesting and technologically relevant magnetic and transport properties that can be systematically controlled by varying the structure of the superlattice periods. Students in this program receive a broad and rigorous training in materials science, chemistry and physics and will have opportunities to spend part of their graduate careers participating in Oregon's Ph.D. internship program which is designed to expose students to the challenges and rewards of industrial research and development.