Lattice tuning of charge and spin transport in $\beta_{12}$-borophene nanoribbons

TL;DR

This paper investigates how lattice vibrations can enhance spin polarization and charge transport in $eta_{12}$-borophene nanoribbons, proposing phonons as a tuning mechanism for borophene-based electronic devices.

Contribution

It introduces a novel approach of using lattice vibrations to control spin and charge transport in borophene nanoribbons, supported by a theoretical model combining electron-phonon interactions and Green's functions.

Findings

Lattice vibrations significantly enhance spin polarization in zigzag borophene nanoribbons.

Phonon interactions modify charge transport, especially in nonmagnetic edge configurations.

Structural distortions lead to anisotropic electron-phonon couplings, affecting transport properties.

Abstract

$\beta_{12}$-borophene nanoribbons (BNRs) exhibit magnetic zigzag edges, while other edge configurations are nonmagnetic. However, when the source, central, and drain regions of a logic device are all composed of zigzag BNRs (ZBNRs), the resulting spin polarization remains weak, unless a high voltage is applied. In this work, we demonstrate that lattice vibrations-introduced for example, via a thermal bath coupled to the central BNR-can enhance spin polarization in ZBNRs. This enhancement manifests as marked changes in the current-voltage characteristics, enabling direct experimental probing. In contrast, nonmagnetic edge configurations exhibit phonon-enhanced charge transport. We employ a tight-binding approach augmented with local electron-phonon interactions described by the Holstein model, and compute the phonon-renormalized Green's functions and transport currents using the Landauer-B\"{u}ttiker formalism. The mechanism is supported by analyzing both spinless and spinful electronic dispersions and the corresponding density of states. Compared to the phonon-free edges, structural distortions lead to anisotropic electron-phonon couplings, which significantly modify both charge and spin transport. These results position phonon as an effective tuning parameter for optimizing borophene-based logic devices via engineered edge configurations.