  Ni-Ga bilayers are a versatile platform for exploring the competition between
strongly antagonistic ferromagnetic and superconducting phases. We characterize
the impact of this competition on the transport properties of highly-ballistic
Al/Al2O3(/EuS)/Ni-Ga tunnel junctions from both experimental and theoretical
points of view. While the conductance spectra of junctions comprising Ni (3
nm)-Ga (60 nm) bilayers can be well understood within the framework of earlier
results, which associate the emerging main conductance maxima with the junction
films' superconducting gaps, thinner Ni (1.6 nm)-Ga (30 nm) bilayers entail
completely different physics, and give rise to novel large-bias (when compared
to the superconducting gap of the thin Al film as a reference) conductance-peak
subseries that we term conductance shoulders. These conductance shoulders might
attract considerable attention also in similar magnetic superconducting bilayer
junctions, as we predict them to offer an experimentally well-accessible
transport signature of superconducting triplet pairings that are induced around
the interface of the Ni-Ga bilayer. We further substantiate this claim
performing complementary polarized neutron reflectometry measurements on the
bilayers, from which we deduce (1) a nonuniform magnetization structure in Ga
in a several nanometer-thick area around the Ni-Ga boundary and can
simultaneously (2) satisfactorily fit the obtained data only considering the
paramagnetic Meissner response scenario. While the latter provides independent
experimental evidence of induced triplet superconductivity inside the Ni-Ga
bilayer, the former might serve as the first experimental hint of its potential
microscopic physical origin.
