Point contact conductance measurements on topological $Bi_2Te_2Se$ and $Bi_2Se_3$ films reveal a signature of superconductivity below 2-3 K. In particular, critical current dips and a robust zero bias conductance peak are observed. The latter suggest
s the presence of zero energy bound states which could be assigned to Majorana Fermions in an unconventional topological superconductor. We attribute these novel observations to proximity induced local superconductivity in the films by small amounts of superconducting Bi inclusions or segregation to the surface, and provide supportive evidence for these effects.
Measurements of the differential conductance spectra of YBa2Cu3O7-SrRuO3 and YBa2Cu3O7-La0.67Ca_0.33MnO3 ramp-type junctions along the node and anti-node directions are reported. The results are consistent with a crossed Andreev reflection effect onl
y in YBa2Cu3O7-SrRuO3 junctions where the domain wall width of SrRuO3 is comparable with the coherence length of YBa2Cu3O7. No such effect was observed in the YBa2Cu3O7-La0.67Ca0.33MnO3 junctions, which is in line with the much larger (x10) domain wall width of La0.67Ca0.33MnO3. We also show that crossed Andreev exists only in the anti-node direction. Furthermore, we find evidence that crossed Andreev in YBa2Cu3O7 junctions is not sensitive to nm-scale interface defects, suggesting that the length scale of the crossed Andreev effect is larger than the coherence length, but still smaller than the La0.67Ca0.33MnO3s domain wall width.
