Exchange-dependent spin polarized transport and phase transition in a triple monomer molecule

Molecular junction contributes significantly to the fundamental understanding of the quantum information technologies in molecular spintronics. In this paper, with the aid of the state of the art numerical renormalization group method, we find a triple monomer molecule structure with strong electron-electron interaction could be a potential candidate for multifunctional spin polarizer when the external magnetic field along $z$ axis is applied. It is demonstrated that the polarizing scenarios depend closely on the inter-orbital exchange couplings, results in several kinds of spin polarizers, e.g., the unidirectional, the bidirectional, the dual, and the ternary spin polarizers. We show in detail the related phase diagram, and conclude the Zeeman effect and the charge switching for the bonding, anti-bonding and non-bonding orbitals are responsible for the spin polarizing transport. We stress even the energy levels are chosen beyond the Kondo regime, such structure still shows a promising platform for molecular spintronics components.