Phase coherent transport and spin-orbit interaction in GaAs/InSb core/shell nanowires

TL;DR

This study investigates phase-coherent transport and spin-orbit effects in GaAs/InSb core-shell nanowires through low-temperature magnetotransport experiments, revealing quantum interference phenomena and their dependence on magnetic fields and gate voltages.

Contribution

It provides new insights into quantum transport phenomena in GaAs/InSb nanowires, including observations of weak antilocalization and flux-periodic conductance oscillations.

Findings

Observation of phase-coherence length from conductance fluctuations.

Detection of weak antilocalization features in magneto-conductance.

Identification of flux-periodic oscillations linked to quantum states in the shell.

Abstract

Low-temperature magnetotransport measurements are performed on GaAs/InSb core-shell nanowires. The nanowires were self-catalyzed grown by molecular beam epitaxy. The conductance measurements as a function of back-gate voltage show an ambipolar behavior comprising an insulating range in between the transition from the p-type to the n-type region. Simulations based on a self-consistent Schr\"odinger--Poisson solver revealed that the ambipolar characteristics originate from a Fermi level dependent occupation of hole and electron states within the approximately circular quantum well formed in the InSb shell. By applying a perpendicular magnetic field with respect to the nanowire axis, conductance fluctuations were observed, which are used to extract the phase-coherence length. By averaging the magneto-conductance traces at different back-gate voltages, weak antilocalization features are resolved. Regular flux-periodic conductance oscillations are measured when an axial magnetic field is applied. These oscillations are attributed to closed-loop quantized states located in the InSb shell which shift their energetic position periodically with the magnetic flux. Possible reasons for experimentally observed variations in the oscillation patterns are discussed using simulation results.