Spin-orbit coupling and phase-coherence in InAs nanowires

TL;DR

This study explores the quantum interference effects and spin-orbit coupling in InAs nanowires through magnetotransport measurements, revealing phase coherence properties and strong spin-orbit interactions at low temperatures.

Contribution

It provides the first detailed analysis of phase coherence length and spin-orbit scattering length in InAs nanowires using magnetoconductance fluctuations and simulations.

Findings

Phase coherence length exceeds 300 nm at low temperatures.

Spin-orbit scattering length is approximately 70 nm.

Weak antilocalization effect observed after averaging over gate voltages.

Abstract

We investigated the magnetotransport of InAs nanowires grown by selective area metal-organic vapor phase epitaxy. In the temperature range between 0.5 and 30 K reproducible fluctuations in the conductance upon variation of the magnetic field or the back-gate voltage are observed, which are attributed to electron interference effects in small disordered conductors. From the correlation field of the magnetoconductance fluctuations the phase-coherence length l_phi is determined. At the lowest temperatures l_phi is found to be at least 300 nm, while for temperatures exceeding 2 K a monotonous decrease of l_phi with temperature is observed. A direct observation of the weak antilocalization effect indicating the presence of spin-orbit coupling is masked by the strong magnetoconductance fluctuations. However, by averaging the magnetoconductance over a range of gate voltages a clear peak in the magnetoconductance due to the weak antilocalization effect was resolved. By comparison of the experimental data to simulations based on a recursive two-dimensional Green's function approach a spin-orbit scattering length of approximately 70 nm was extracted, indicating the presence of strong spin-orbit coupling.