Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures

TL;DR

This study investigates defected graphene/silicene nanoribbon heterostructures, demonstrating their potential for high-efficiency spin caloritronic devices through defect engineering and external field tuning, with near-perfect spin filtering and high spin polarization.

Contribution

It introduces the use of divacancy defects in graphene/silicene nanoribbons to enhance thermoelectric and spin filtering properties, providing a new approach for spin caloritronic device design.

Findings

Almost perfect thermal spin filtering effect achieved.

Spin polarization efficiency exceeds 99.99%.

Large spin-dependent Seebeck coefficient of 1.2 mV/K.

Abstract

The main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Greens function (NEGF) approach. To further study the thermoelectric (TE) properties of the GSNRs, three defect arrangements of divacancies (DVs) are also considered for a larger system, and their responses are re-evaluated. The results demonstrate that the defected GSNRs with the DVs can provide an almost perfect thermal spin filtering effect (SFE), and spin switching. A negative differential thermoelectric resistance (NDTR) effect and high spin polarization efficiency (SPE) larger than 99.99 percent are obtained. The system with the DV defects can show a large spin-dependent Seebeck coefficient, equal to 1.2 mV/K, which is relatively large and acceptable. Appropriate thermal and electronic properties of the GSNRs can also be obtained by tuning up the DV orientation in the device region. Accordingly, the step-like GSNRs can be employed to produce high efficiency spin caloritronic devices with various features in practical applications.