Spin-orbit interaction in tubular prismatic nanowires

TL;DR

This paper provides a theoretical analysis of spin-orbit interaction effects in prismatic nanowires with polygonal cross sections, revealing geometry-dependent electronic properties and potential for enhanced spin-orbit coupling.

Contribution

It introduces a detailed theoretical model of spin-orbit interaction in tubular prismatic nanowires, highlighting the influence of geometry and material intermixing on electronic states.

Findings

Spin-orbit splitting varies significantly with wire geometry.

Triangular shells can act as three independent low-energy wires.

Material intermixing enhances spin-orbit coupling effects.

Abstract

We theoretically study the spin-orbit interaction in the outer regions of core-shell nanowires that can act as tubular, prismatic conductors. The polygonal cross section of these wires induces non-uniform electron localization along the wire perimeter. In particular, low-energy electrons accumulate in the corner regions, and in the case of narrow shells, conductive channels form along the sharp edges. In contrast, higher-energy electrons are shifted toward the facets. These two groups of states may be separated by large energy gaps, which can exceed the room-temperature energy in the case of triangular geometries. We compare the impact of spin-orbit interaction on the corner and side states of hexagonal and triangular shells grown on hexagonal cores as well as on triangular shells grown on triangular cores. We find that the spin-orbit splitting, and thus the degeneracy of energy states at finite wave vectors, strongly depend on the tube's geometry. We demonstrate that the weak spin-orbit coupling observed in clean wires can be significantly enhanced if the intermixing of core and shell materials takes place. Moreover, we show that the energy spectrum in the presence of spin-orbit interaction allows for estimating the interaction between states and shows that triangular shells can act as three independent wires in the low-energy regime, while they behave as interacting systems at higher-energy ranges.