  Artificially engineered topological superconductivity has emerged as a viable
route to create Majorana modes, exotic quasiparticles which have raised great
expectations for storing and manipulating information in topological quantum
computational schemes. The essential ingredients for their realization are spin
non-degenerate metallic states proximitized to an s-wave superconductor. In
this context, proximity-induced superconductivity in materials with a sizable
spin-orbit coupling has been heavily investigated in recent years. Although
there is convincing evidence that superconductivity may indeed be induced, it
has been difficult to elucidate its topological nature. In this work, we
systematically engineer an artificial topological superconductor by
progressively introducing superconductivity (Nb) into metals with strong
spin-orbital coupling (Pt) and 3D topological surface states (Bi2Te3). Through
a longitudinal study of the character of superconducting vortices within s-wave
superconducting Nb and proximity-coupled Nb/Pt and Nb/Bi2Te3, we detect the
emergence of a zero-bias peak that is directly linked to the presence of
topological surface states. Supported by a detailed theoretical model, our
results are rationalized in terms of competing energy trends which are found to
impose an upper limit to the size of the minigap separating Majorana and
trivial modes, its size being ultimately linked to fundamental materials
properties.
