Abstract by Alden Pack
Physics and Astronomy
Analyzing the Metastability of Superconductors Using Automatic Differentiation
A defining characteristic of superconductivity is the Meissner effect, i.e., expulsion of applied magnetic fields. For large fields, the Meissner effect breaks down and the superconductor transitions to a normal metal. The theoretical upper limit is known as the "superheating field", above which magnetic vortices spontaneously enter the superconductor. Particle accelerators use alternating electric fields in superconducting resonance cavities to accelerate charged particles. The absolute limit to cavity performance occurs when the induced magnetic field reaches the superheating field. I calculate both the superheating field and the vortex spacing using a linear stability analysis. I use automatic differentiation to calculate derivatives of complex free energy functionals. This approach will enable material specific predictions using sophisticated models of superconductivity.