Proximity effects and finite-quasiparticle-lifetime effects in normal metal/ferromagnetic semiconductor/superconductor structures

Proximity effects and finite-quasiparticle-lifetime effects in normal metal/ferromagnetic semiconductor/superconductor (NM/FS/SC) junctions are studied based on an extended Blonder–Tinkham–Klapwijk (BTK) theory. It is shown that the dependence of the conductance spectra on the exchange energy in FS and the thickness of FS for the heavy holes is much different from that for the light holes due to the different mismatches in the effective mass and Fermi velocity between FS and SC. The finite quasiparticle lifetime can induce a broadened normalized conductance and a reduced superconducting gap and lead to a smearing of the dips in the conductance arising from the proximity-effect induced superconductivity in FS interlayer.