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arXiv · 2511.09903

Enhanced Thermoelectricity in Nanowires with inhomogeneous Helical states

Zahra Aslani·Fabio Taddei·Fabrizio Dolcini·Alessandro Braggio
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Abstract

Semiconductor nanowires (NWs) with strong Rashba spin-orbit coupling (RSOC), when exposed to a suitably applied Zeeman field, exhibit one-dimensional helical channels with a spin orientation locked to the propagation direction within the magnetic energy gap. Here, by adopting a scattering-matrix approach applied to a tight-binding model of the NW, we demonstrate that the thermoelectric (TE) properties can be widely controlled by tuning the misalignment angle $\phi$ between the spin-orbit directions of two NW segments. In particular, when the RSOC vectors are antiparallel (Dirac paradox configuration) we predict a significant violation of the Wiedemann-Franz law, and a strong enhancement of the Seebeck coefficient and the $ZT$ figure of merit. We also show that the Zeeman gap determines the optimal energy window for doping and temperatures. These results suggest that controlling the spin-orbit field direction, which can be achieved with suitably applied wrap gates, is a promising alternative for tuning and optimizing the TE response in quantum-coherent semiconducting NW devices.

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Zahra Aslani, Fabio Taddei, Fabrizio Dolcini, Alessandro Braggio. 2025-11-13. Enhanced Thermoelectricity in Nanowires with inhomogeneous Helical states. https://doi.org/10.1103/mz9c-272x

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