Charge transport in two-dimensional electron gas/insulator/superconductor junctions with Rashba spin-orbit coupling

We have studied the tunneling conductance in two-dimensional electron gas/insulator/superconductor junctions in the presence of Rashba spin-orbit coupling (RSOC). It is found that for low insulating barriers the tunneling conductance is suppressed by the RSOC while for high insulating barriers it is almost independent of the RSOC. We also find reentrant behavior of the conductance at zero voltage as a function of the RSOC for intermediate insulating barrier strengths. The results are essentially different from those predicted in ferromagnet/superconductor junctions. The present derivation of the conductance is applicable to arbitrary velocity operators with off-diagonal components.

Figure 1

(Color online) Schematic illustration of Rashba and Zeeman splitting.

Figure 2

(Color online) Schematic illustration of scattering processes.

Figure 3

(Color online) Normalized tunneling conductance with $Z=10$ (a), 1 (b), and 0 (c).

Figure 4

Tunneling conductance for superconducting states at zero voltage as a function of RSOC in 2DEG/S junctions (left panels) and the exchange field in F/S junctions (right panels) with $Z=10$ (a), (d), 1 (b), (e), and 0 (c), (f). Here $\beta =2m\lambda ∕{\hslash }^2{k}_F$.

Figure 5

(Color online) The angular averaged Andreev and normal reflection probabilities for $Z=10$. $A_1$, $A_2$, $B_1$, and $B_2$ are AR probabilities. $C_1$, $C_2$, $D_1$, and $D_2$ are normal reflection probabilities.

Figure 6

(Color online) The angular averaged Andreev and normal reflection probabilities for $Z=0$. $A_1$, $A_2$, $B_1$, and $B_2$ are AR probabilities. $C_1$, $C_2$, $D_1$, and $D_2$ are normal reflection probabilities.