Controlling Superconductivity via Strain and Doping

with Dr. Betül Pamuk
Assistant Professor, Williams College

ABSTRACT: Superconductivity is one of the most fascinating quantum states of matter with many interesting applications from low temperature electronics to quantum computing, from magnetic resonance imaging to high speed trains. However, a detailed understanding of how one can theoretically predict and deterministically enhance the superconducting transition temperature (Tc) by design remains elusive. Recent developments in computational techniques present a possibility to gain insights into the electronic and vibrational properties of materials and their coupling. Combined with modern approaches in materials science such as epitaxial straining, chemical doping, gating, heterostructuring, nanopatterning, these computational techniques can allow for tailored control of superconductivity. In this talk, I will give three examples of controlling superconductivity. First, I will show how straining RuO2 thin films on TiO2 substrates can stabilize superconductivity on normally non-superconducting RuO2, by changing its electronic and vibrational properties, and propose a more detailed study of this phenomena. Next, I will describe how doping semiconducting transition metal chloro-nitrides, such as ZrNCl and HfNCl, stabilizes superconductivity and how Tc increases at the low doping regime, and propose an extension of this study to other halide-nitrides. Finally, I will present the first experimental measurement of the electronic structure of NbN, a century-old superconductor, discuss possible theoretical challenges to understanding the details of this material, and propose enhancing the Tc of other transition metal nitrides, such as TiN, via strain and doping. This talk will demonstrate how novel computational and theoretical calculations allow us to better understand the electronic and vibrational interactions in materials and how one can control superconductivity by using different knobs.

BIOGRAPHY: Dr. Betül Pamuk has obtained her B.S. (2008) degree from Bilkent University; and M.A. (2011) and Ph.D. (2014) degrees from Stony Brook University. She was a postdoctoral researcher at Sorbonne Université, Pierre et Marie Curie (2014–2016) and a research associate at Cornell University working as a staff scientist for the theory facility of the PARADIM platform (2017-2024). She has been an assistant professor of physics at Williams College since 2024. Her research area is computational condensed matter physics and materials science using first-principles calculations. She has been focused on understanding the effect of phonons on the atomic and electronic structure of materials.

With refreshments from Panera Bread