Geometric symmetry modulated spin polarization of electron transport in graphene-like zigzag FeB2 nanoribbons

Abstract

Due to electron deficiency, the graphene-like honeycomb structure of boron is unstable. By introducing Fe atoms, it is reported that FeB2 monolayer has excellent dynamic and thermal stabilities at room temperature. Based on first-principles calculations, the spin-dependent transport of zigzag FeB2 nanoribbons (ZFeB2NRs) under ferromagnetic state (FM) is investigated. It is found that, around the Fermi level, FeB-terminated (or FeFe-terminated) ZFeB2NRs exhibit completely spin-polarized (or spin-unpolarized) transmission, and BB-terminated configurations exhibit completely unpolarized or partially polarized transmission. Further analysis shows that, the hinge dihedral angle has a switching effect on the transport channels, and the spin polarization of the transmission is determined by the symmetry of the distribution of hinge dihedral angles along the transverse direction of the ribbon, where symmetric/asymmetric distribution induces spin-unpolarized/polarized transmission. Moreover, such a symmetry effect is found to be robust to the width of the ribbon, showing great application potential. Our findings may throw light on the development of B-based spintronic devices.