Spin-polarized quantum transport in latterly connected zigzag-triangular graphene nanodots

Abstract

Spintronic devices with enhanced spin quantum transport are crucial for future computing technology. Here we investigate the magnetic, electro-optical, and transport properties of 2D chains from laterally connected zigzag triangular graphene (ZTG) nanodots using first principle calculations. The optimized structures show that ZTG connected with an even number of C-atoms have a planer structure while those linked with odd numbers experience noticeable twisting. The twisting can be removed by considering the effect of the substrate due to van der Waals interactions with the substrate. Vibrational frequencies and binding energies confirmed the structural stability of the considered ZTG chains. The ZTG chains have ferromagnetic spin ordering proportional to the number of linked ZTG that can even increase in odd-linked chains due to the unpaired electrons from the odd link. For instance, 3ZTG coupled by an even link (2C) is a ferromagnetic chain coupled by a nonmagnetic link while odd linking (3C) results in a ferromagnetic chain with higher net spin and ferromagnetic coupling. The I–V curves indicate that the current in the latter chain is significantly higher than that in the former, especially for the spin-up current. Moreover, its transmission spectra reveal only one sharp spin-up peak within the bias window at an applied voltage of 1.5 V. Therefore, the considered ZTG chains with odd links are promising spin filters for spintronic applications.