Andreev reflection in a mesoscopic hybrid four-terminal Rashba ring

The transport properties of a mesoscopic hybrid four-terminal Rashba ring are investigated along the lines of Blonder, Tinkham and Klapwijk and our attention is focused on the influence of Andreev reflection. Although the resonant peak and zero conductance resulting from spin-dependent quantum interference are destroyed by incoherent addition in this four-terminal structure, the total longitudinal electron conductance is still enhanced by the Andreev contribution. However, the contribution of the Andreev reflection to the spin Hall conductance in this mesoscopic Rashba ring is negative and the total spin Hall conductance is reduced. These results are robust to an external magnetic flux