Carsten Timm: Theory of superconductivity
Carsten Timm: Theory of superconductivity
Carsten Timm: Theory of superconductivity
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
S<br />
N<br />
S<br />
2∆<br />
0<br />
2eV<br />
eV<br />
In particular, an electron-like quasiparticle from an occupied state below the gap in, say, the left superconductor<br />
can after multiple reflections emerge in a previously unoccupied state above the gap in the right superconductor.<br />
A new transport channel becomes available whenever the full gap 2∆ 0 is an odd integer multiple <strong>of</strong> eV :<br />
2∆ 0 = (2n + 1) eV, n = 0, 1, . . . (11.104)<br />
⇒ eV = ∆ 0<br />
n + 1 , n = 0, 1, . . . (11.105)<br />
2<br />
The case n = 0 corresponds to direct quasiparticle transfer from one superconductor to the other, similar to<br />
quasiparticle tunneling in a superconductor-insulator-superconductor junction. The opening <strong>of</strong> new transport<br />
channels for n = 0, 1, . . . , i.e., at<br />
eV = 2 3 ∆ 0, 2 5 ∆ 0, 2 7 ∆ 0, . . . (11.106)<br />
leads to structures in the current-voltage characteristics below the gap, specifically to peaks in the differential<br />
conductance dI/dV .<br />
dI<br />
dV<br />
∆ 0<br />
2<br />
3 ∆ 0<br />
2<br />
5 ∆ 0<br />
− 2 0<br />
2 eV<br />
∆ 0<br />
119