Detection of spin bias by quantum interference effect in a Rashba ring

We propose to use the quantum interference effect in a Rashba ring to detect the pure spin current driven by a spin bias. By means of the Keldysh Green's function method, we demonstrated that a tunneling charge current could be induced flowing through the ring due to the combined quantum interference effect of the electron spin precession phase from Rashba spin-orbit coupling (RSOC) and the electron traveling phase difference in the two arms of the ring. The nonzero charge current can be used to deduce not only the magnitude of the spin bias but also its spin polarization. This charge current depends on some system parameters such as RSOC strength and the asymmetry of two arms. Our proposal may provide a practical and all-electrical way to indirectly detect the pure spin current (spin bias) by measuring the induced charge current/bias in a Rashba ring. © 2009 Europhysics Letters Association.