Manipulating 2D Superconductivity through atomic scale control of boundary conditions

University Of Texas At Austin, Austin TX

Investigators

Abstract

NON-TECHNICAL ABSTRACT: This proposal is aimed at controlling the properties of thin superconductor films in the range of only a few atomic monolayers and studying the superconducting properties in this new regime. The superconducting films in such a thin regime are likely to exhibit properties that are not found in the bulk form. For example, such a thin film may be able to carry supercurrent in the presence of very high magnetic fields making the film much more useful for device applications. The research activities involve state-of-the-art synthesis techniques that can lay down the thin film atomic layer by atomic layer thus enabling us to achieve the ultimate material control at the microscopic scale. In addition, we will use characterization tools to study the superconducting properties from nanometer to macroscopic (millimeter) length scales. The proposal focuses on the integration of research and education to train internationally competitive students in materials research. We are also committed to educational outreach to broader audiences at all levels. At UT-Austin the PI will take advantage of the Summer Academy of Nanoscience and Nanotechnology for state-wide high school teachers and students, previously established under the IGERT program. Moreover, we will offer summer internship opportunities for female high school students through the Alice in the Wonderland program; the PI has already hosted four of these students as summer interns and will continue to do so in future years. Finally, this program is fully committed to broadening participation of under-represented groups in graduate research with specific goals of increasing the percentage of graduate students that are women or/and of Hispanic background. TECHNICAL ABSTRACT: Elegantly fabricated functional materials with reduced dimensions occupy a central stage of modern materials research. Supported by an NSF-FRG program in the past, the PI has been focusing on the novel physical properties of precisely tailored metallic thin films and related nanostructures in the quantum regime. These past efforts have substantially advanced the field in terms of growth and characterization of such structures. In the proposed program, we will take another leap forward by creating new heterostructures based on these quantum films to explore and harness their emergent exotic superconducting properties for potential applications. Specifically, we will focus on the interplay of superconductivity with three different quantum degrees of freedom, including electronic, lattice, and spin, and we will implement the following four major task areas: (a) Correlating microscopic and macroscopic measurements - manipulating structural defects and investigating their roles on phase fluctuations; (b) Revisiting quantum size effect on superconductivity ultra-thin films and unraveling the quantum confinement of phonons; (c) Tuning superconductivity of atomic-layer superconducting films with interfacial engineering; and (d) Exploring superconducting - spin-paramagnetic (SC-SP) transition in ultra-thin epitaxial films.