Nanohelices as superlattices: Bloch oscillations and electric dipole transitions

TL;DR

This paper theoretically explores nanohelices under electric fields, revealing tunable superlattice behavior, Bloch oscillations, negative differential conductance, and terahertz-range dipole transitions, with potential applications in optoelectronics.

Contribution

It introduces a theoretical model of nanohelices exhibiting superlattice effects, Bloch oscillations, and tunable dipole transitions, including a novel photogalvanic effect under circularly polarized light.

Findings

Observation of Bloch oscillations in nanohelices

Negative differential conductance under combined electric fields

Tunable terahertz-range dipole transitions

Abstract

Subjecting a nanohelix to a transverse electric field gives rise to superlattice behavior with tunable electronic properties. We theoretically investigate such a system and find Bloch oscillations and negative differential conductance when a longitudinal electric field (along the nanohelix axis) is also applied. Furthermore, we study dipole transitions across the transverse-electric-field-induced energy gap, which can be tuned to the eulogized terahertz frequency range by experimentally attainable external fields. We also reveal a photogalvanic effect by shining circularly polarized light onto our helical quantum wire.