Point contact Andreev reflection spectroscopy on ferromagnet/superconductor bilayers

We performed point contact spectroscopy experiment by pushing gold tip on the ferromagnetic side of Nb/Pd0.84Ni0.16 bilayers. Several contacts have been measured at temperature 4.2 K evidencing a wide variety of features (zero bias peak, conductance dips, etc.) appearing in the differential conductance spectra at energies up to Nb energy gap. A theoretical model has been developed within the scattering theory for ferromagnetic/superconductor heterostructures to fit experimental data. All different features can be consistently explained in our model by taking into account the spin polarization as well as the thickness of the ferromagnetic layer. We also show that we can give very precise estimation of such ferromagnetic characteristics. (C) 2014 Elsevier B.V. All rights reserved.