Persistent Spin and Charge Currents in Open Conducting Ring Subjected to Rashba Spin--Orbit Coupling

We investigate persistent charge and spin currents of a one-dimensional ring with Rashba spin--orbit coupling and connected asymmetrically to two external leads spanned with angle φ₀. Because of the asymmetry of the structure and the spin-reflection, the persistent charge and spin currents can
be induced. The magnification of persistent currents can be obtained when tuning the energy of incident electron to the sharp zero and sharp resonance of transmission depending on the Aharonov--Casher (AC) phase due to the spin--orbit coupling and the angle spanned by two leads φ₀. The general dependence of the charge and spin persistent currents on these parameters is obtained. This suggests a possible method of controlling the magnitude and direction of persistent currents by tuning the AC phase and φ₀, without the electromagnetic flux though the ring.