Spin Hall and Edelstein effects in a ballistic quantum dot with Rashba spin-orbit coupling

We study spin-resolved transport in a ballistic quantum dot with Rashba spin–orbit cou-pling, focusing on charge-to-spin conversion and spin Hall effect. In the regime where the dot size is comparable to the Fermi wavelength, we identify a clear crossover from a resonance-mediated weak localization regime to weak antilocalization regime as the Rashba coupling increases. This transition is accompanied by gate-tunable spin currents of Edelstein and spin Hall type, whose behavior reflects the underlying electron wave-function interference. Notably, the Edelstein current shows an inflection point at the critical Rashba strength, signaling the crossover from weak localization to weak antilo-calization. In the presence of an in-plane magnetic field we also report a transition in angular periodicity of the magnetoresistance –from π to 2π– arising from the interplay between spin–orbit interaction and Zeeman coupling. These results establish a direct link between quantum coherence, charge-to-spin conversion, and geometric confinement in mesoscopic systems.