Gate-tunable superconductor-semiconductor coupling and its consequence on zero-energy modes in PbTe-Pb nanowires

Superconductor-semiconductor coupling in hybrid nanowires plays an essential role in Majorana devices. Here, we demonstrate strong tunability of this coupling strength in PbTe-Pb nanowires and how it affects the induced gap and zero bias conductance peaks (ZBPs). We first tune the device into the "strong coupling regime", revealing a hard superconducting gap. Both robust and non-robust ZBPs appear in distinct field ranges. In contrast, setting the gate voltage more positive drives the device into the "weak coupling regime", where the gap becomes small and soft. Consequently, robust ZBPs disappear while non-robust ones remain. These results build a direct link between tunable coupling and robust ZBPs, shedding lights on possible Majorana signatures in PbTe-Pb devices.