Enhanced spin-orbit coupling in core/shell nanowires

TL;DR

This study investigates how the interface area in core/shell nanowires enhances spin-orbit coupling, affecting electron spin dynamics and relaxation, with implications for spintronic applications.

Contribution

It demonstrates the significant role of interface-induced SOC in core/shell nanowires, providing a new tuning mechanism for spin-orbitronic devices.

Findings

Optical spin injection into single nanowires demonstrated

Anisotropic spin relaxation observed in magnetic fields

Model highlights interface-induced SOC as dominant factor

Abstract

The spin-orbit coupling (SOC) in semiconductors is strongly influenced by structural asymmetries, as prominently observed in bulk crystal structures that lack inversion symmetry. Here, we study an additional effect on the SOC: the asymmetry induced by the large interface area between a nanowire core and its surrounding shell. Our experiments on purely wurtzite GaAs/AlGaAs core/shell nanowires demonstrate optical spin injection into a single free-standing nanowire and determine the effective electron g-factor of the hexagonal GaAs wurtzite phase. The spin relaxation is highly anisotropic in time-resolved micro-photoluminescence measurements on single nanowires, showing a significant increase of spin relaxation in external magnetic fields. This behavior is counterintuitive compared to bulk wurtzite crystals. We present a model for the observed electron spin dynamics highlighting the dominant role of the interface-induced SOC in these core/shell nanowires. This enhanced SOC may represent an interesting tuning parameter for the implementation of spin-orbitronic concepts in semiconductor-based structures.