We study Andreev reflection and Josephson currents in topological bilayer exciton condensates (TECs). These systems can create 100% spin-entangled nonlocal currents with high amplitudes due to perfect nonlocal Andreev reflection. This Andreev reflection process can be gate tuned from a regime of purely retro reflection to purely specular reflection. We have studied the bound states in TEC–topological-insulator–TEC Josephson junctions and find a gapless dispersion for perpendicular incidence. The presence of a sharp transition in the supercurrent-phase relationship when the system is in equilibrium is a signature of fractional charge, which can be further revealed in ac measurements faster than relaxation processes via Landau-Zener processes.
|Number of pages||6|
|Journal||Physical Review B (Condensed Matter and Materials Physics)|
|Publication status||Published - 2014|
Veldhorst, M., Hoek, M., Snelder, M., Hilgenkamp, H., Golubov, A. A., & Brinkman, A. (2014). Nonlocal spin-entangled Andreev reflection, fractional charge and current-phase relations in topological bilayer-exciton-condensate junctions. Physical Review B (Condensed Matter and Materials Physics), 90(035428), -. . https://doi.org/10.1103/PhysRevB.90.035428