Physics Colloquium

Prof. Nadya Mason, University of Illinois at Urbana-Champaign

"Designing Superconductivity: Manipulating Interactions in Arrays of Superconducting Islands"

4:00pm, The John A. Wheeler Lecture Hall (RLM 4.102). Coffee and cookies will be served at 3:45pm in RLM 4.102

Abstract: One of the most fundamental questions in physics is how the macroscopic properties of matter emerge from microscopic constituents. Often, complex electronic correlations at the micro-scale act to create remarkable macroscopic materials properties, such as superconductivity and ferromagnetism. But the parameters relevant to understanding and manipulating these correlations are difficult to access. In this talk, I will discuss a “bottom-up” approach to studying collective effects in matter via nanostructured arrays of superconducting islands. We fabricate large arrays of superconducting islands patterned on normal metal films; by changing the size and configuration of the islands, we can to tune the parameters relevant to 2D superconductivity, such as disorder, dissipation, and phase separation. I will discuss electrical transport measurements of these systems, including characterization of the superconducting transitions, vortex dynamics in finite magnetic-fields, and evidence that the system approaches an unusual metallic ground state as the island spacing is increased. I will also discuss the mechanism behind the suppression of superconductivity in individual granular islands, even at large diameters.