Enhanced spin-orbit coupling in core/shell nanowires

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.

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• Enhanced Rashba spin-orbit coupling in core-shell nanowires by the interfacial effect
• Persistent spin textures and currents in wurtzite nanowire-based quantum structures
• Common nonlinear features and spin-orbit coupling effects in the Zeeman splitting of novel wurtzite materials
• Ultralong spin lifetimes in one-dimensional semiconductor nanowires
• Unusual spin properties of InP wurtzite nanowires revealed by Zeeman splitting spectroscopy
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• Low-symmetry nanowire cross-sections for enhanced Dresselhaus spin-orbit interaction
• Wurtzite quantum wires with strong spatial confinement: polarization anisotropies in single wire spectroscopy