Spin-orbital coupling effect on Josephson current through a superconductor heterojunction

We study the spin-orbital coupling effect on the Josephson current through a superconductor (SC) heterojunction, consisting of two s-wave superconductors and a two-dimensional electron gas (2DEG) layer between them. The Rashba-type (RSOC) and/or Dresselhaus-type (DSOC) of spin-orbital coupling are considered in the 2DEG region. By using a tight-binding model and Green's function method, we calculate the dc supercurrent flowing through the junction and find that the critical current I-c exhibits a damped oscillation with both the strength of SOC and the layer length of 2DEG; especially, the strength ratio between RSOC and DSOC can also induce switching between the 0 state and the pi state of the SC/2DEG/SC junction as well. This 0-pi transition results from the fact that SOC in a two-dimension system can lead to a pseudomagnetic effect on the flowing electrons like the effect of a ferromagnet, since the time-reversal symmetry of the system has already been broken by two SC leads with different macroscopic phases. (C) 2008 American Institute of Physics.