Controllable spin filtering and half metallicity in $\beta_{12}$-borophene nanoribbons

TL;DR

This study demonstrates that $eta_{12}$-borophene nanoribbons can be electrically controlled to exhibit spin filtering and half-metallicity, making them promising for spintronic applications due to their robust spin transport properties.

Contribution

The paper introduces a method to control spin filtering and half-metallicity in $eta_{12}$-borophene nanoribbons using external fields and edge manipulations, highlighting their potential in spintronics.

Findings

Spin filtering occurs for both spin-up and spin-down electrons with a nonlocal exchange magnetic field.

Armchair BNRs exhibit electrically controllable half-metallicity under combined electric and exchange fields.

Edge manipulations lead to giant magnetoresistance and perfect spin filtering, resilient to disorder and vacancies.

Abstract

The experimental observation of the Dirac fermion states in $\beta_{12}$-borophene sheets and the discovery of their novel topological properties properties have made them a promising candidate for spintronic applications. Here, by combining non-equilibrium Green's function (NEGF) and tight-binding (TB) approximation, we study the charge and spin transport properties through a $\beta_{12}$-borophene nanoribbon (BNR) with the different edge shapes. We show when a BNR exposed to a nonlocal exchange magnetic field, the spin filtering occurs for both spin-up and spin-down so that the spin direction of transmitted electrons could be controlled by adjusting the energy of incoming electrons with the help of an external backgate voltage. It is found that an armchair BNR (ABNR) in the simultaneous presence of a transverse electric field and a nonlocal exchange field indicates a half-metallic nature which is electrically controllable. Moreover, the influence of local exchange field fields is evaluated by exposing the edges of ABNR to ferromagnetic strips with parallel and antiparallel configurations. Our findings show that the edge manipulations in ABNRs lead to the emergence of a giant magnetoresistance and a perfect spin filter. Finally, we studied the effects of edge vacancies and Anderson disorder on the spin-dependent conductance of an ABNR and find that the perfect spin polarization is not destroyed in the presence of Anderson disorder and various single vacancies. Our results reveal the outstanding spin transport properties of ABNRs for future spintronic devices.