  Planar tunneling junctions of the presumably unconventional superconductor
FeSe were prepared and investigated. The junctions consisted of FeSe/AlOx/Ag
multilayers patterned lithographically into mesa structures. Bias voltage
dependent differential conductivities dI/dV(V) of junctions in the tunneling,
intermediate barrier strength, and metallic regimes were investigated.
Depending on the barrier type between two and four features of the conductivity
were obtained, which are discussed in the framework of multiple superconducting
energy gaps. Specifically we reproduced with all barrier types an established
energy gap and discovered an additional large gap structure. From two further
conductivity features presumable one originates from another superconducting
gap and the other from resonant states.
