Nonlocal conductivity, continued fractions, and current vortices in electron fluids

Spatial current patterns observed on the macroscale encode information about carrier dynamics on the microscale. In particular, vortices, manifested through currents flowing against externally applied electric fields, attract interest as a telltale signature of electron hydrodynamics. Previous studies have often regarded vorticity as a distinct feature of the hydrodynamic phase. Here, the authors explore the conditions under which vortex patterns can arise in electron systems, finding that the requirements for vortices prove to be considerably less stringent than previous work have suggested.