We have the pleasure to welcome Joshua Heath, Dartmouth College to give a talk on Universal physics in strongly interacting superconductors
The superconducting phase is a macroscopic quantum state defined by the absence of electrical resistance and the expulsion of an external magnetic field, all below some critical temperature Tc. Although the conventional (i.e., BCS) theory of superconductors is well understood, the underlying mechanism for high-Tc superconductivity remains unknown, limiting further progress for a wide class of more unconventional and exotic superconducting materials.
In this talk, I will discuss my recent work on superconductivity at Dartmouth College, in which we aim to better understand the microscopic origin of the Homes scaling law. Homes' law connects zero-temperature superconducting behavior with normal-state transport properties just above the critical temperature, and has been put forward as a universal fingerprint of high-Tc physics in the clean limit. We consider such scaling behavior in the context of Eliashberg theory, which goes far beyond BCS theory by incorporating a dynamical gap induced by electron-phonon interactions. We find that strong electron-phonon interactions behave similarly to some finite impurity concentration. This decreases the T=0 superfluid density and restores a Homes scaling relation in the clean limit, irrespective of a high-critical temperature or Planckian dissipation in the normal phase. We argue that Homes scaling emerges as the result of a non-Galilean-invariant interaction mediated by dispersionless phonons, and is thus a more universal feature of superconductors than previously considered.