Superconducting Diode Effect in Multiphase Superconductors

We identify a new mechanism for the intrinsic superconducting diode effect (SDE) in multiphase superconductors, i.e. materials with multiple neighboring superconducting phases in their phase diagrams. Using a Ginzburg-Landau and a microscopic two-band model, we find phase transitions into a mixed phase with finite-momentum Cooper pairs (including FFLO or pair-density wave/PDW states) and SDE with high (including maximal) diode efficiencies, despite the individual phases exhibiting no SDE and equal inversion parity. We thus show that parity mixing − invoked in previous proposals − is not a crucial ingredient for SDE. The new mechanism may be relevant in a multitude of known multiphase superconductors like UTe₂ and CeRh₂As₂.