Superballistic flow of viscous electron fluid induced by edge magnetoplasmons in point contacts.

In narrow conductors, electron-electron collisions can create a viscous fluid state, allowing conductivity beyond ballistic transport into the superballistic regime. Point contacts made from ultrahigh-mobility two-dimensional electron gas serve as a platform to study this effect. Under microwave irradiation, edge magnetoplasmons in point contacts are excited and strongly influence electron dynamics. This study uses photoconductivity signals - changes from microwave exposure - to investigate superballistic electron flow, confirmed by size-dependent photoconductivity, magnetic field effects, and microwave power analysis. At low magnetic fields, weak microwaves lead to positive photoconductivity due to superballistic flow, while strong radiation causes negative photoconductivity because of enhanced phonon scattering.