Multichannel scattering mechanism behind the reentrant conductance feature in nanowires subject to strong spin-orbit coupling

The characterization of helical states can be performed by checking the existence of the reentrant behavior, which appears as a dip in the conductance probed in nanowires (NWs) with strong spin-orbit coupling (SOC) and under a perpendicular magnetic field. Yet puzzling experimental results report the observation of the re-entrant behavior also in the absence of magnetic fields, ascribed to unconventional spin-flipping two-particle backscattering. We theoretically demonstrate that the observation of the conductance dip can be explained through a multichannel scattering mechanism, which causes a reduction of the transmission when an effective attractive potential and coupling between different channels are present. Both ingredients are provided by the SOC in the transport properties of NWs. The relative effect of the sharpness of interfaces and external fields has also been assessed. The reduction of symmetry constraints of the NW is analyzed and proved to be important in the tuning of the reentrant characteristic.