2-2. Innovation in Materials Genome Engineering – an Experimental Atomistic Perspective

Frank Tsui
Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, NC 27599, USA 

Abstract: Materials genome engineering as a practicing branch of materials science is very much in its infancy. Unlike its human/biological counterparts, where the natural evolutionary processes have already produced the materials, innovations and discoveries in materials genome engineering should necessarily have a focus on new materials and properties that nature hasn’t produced. Artificially structured/engineered materials have enabled innovations and advances in science and technology that have changed the world we live in, and they will continue to do so. From semiconductor quantum wells, to cuprate superconductors, to superalloys, ... materials scientists and engineers have employed chemical doping/alloying, confinement, topology, and processing conditions and other constraints to manipulate materials and functionalities. Materials science and engineering has continued to be focused on exploring and understanding relationships between materials and properties, structures and functionalities, and fundamental processes that control them, very similar to biological counterparts. Advances in combinatorial molecular-beam-epitaxy (MBE) techniques have made it possible for a large number of combinations of artificially structured materials to be grown on a single substrate and synthesized on an atomic scale. Specifically, thin films and superlattices of two ternary compounds can be artificially sequenced/deposited one atomic layer at a time, while a large number of these sequences/combinations can be grown on the same substrate at the same time and thus under the same set of conditions and constraints. The atomic layer-by-layer sequencing technique opens a wide range of opportunities for non-equilibrium engineering of band structures, interfacial states, and other novel phenomena. In this talk, we describe how is the technique being applied to the combinatorial synthesis and characterization of half-metallic and semiconducting Heusler compounds. Significant progress has been made in developing the instrumentation for controlled combinatorial MBE synthesis and powerful high throughput characterization tools to probe, resolve and quantify structural and chemical ordering in these materials, including lattice site specific elemental occupancies. Atomic scale synthesis would necessitate atomic scale element specific characterization. The objective for this type of engineered materials is to realize a combination of electronic and magnetic functionalities and tunability that is not present in any currently known materials but is extremely desirable for future quantum information science and technologies. The work provides a unique perspective into the prospects of innovations and advances in materials genome engineering.