Spin-Dependent Transport in One-Dimensional Mercury- and Silver-Mediated DNA Nanowires
Metallo-DNA nanowires serve as a versatile, programmable scaffold for molecular-scale electronics. In this work, we demonstrate that periodic heavy-metal coordination fundamentally reshapes the electronic landscape of DNA, generating dispersive, metal-centered conduction bands rather than isolated localized states. Driven by enhanced inter-layer coupling, where second nearest-neighbor hopping plays a crucial role: the conduction bandwidth can approach 1 eV, more than double that of canonical DNA. These broad bands suggest enhanced robustness of transport against structural fluctuations. As a result of relativistic effects, in these quasi-one-dimensional materials, spin-orbit (SO) coupling enhances band dispersion and governs spin-dependent transport. We predict that although ligand hybridization reduces atomic SO splitting, the effective SO splitting in these nanowires is comparable to the next-nearest-neighbor hopping strength, which results in considerable spin mixing. We find that Hg2+-coordinated nanowire exhibit pronounced spin-flip conductance comparable to spin-conserving conductance across the LUMO manifold. This efficient spin conversion remains robust over extended molecular lengths and is accompanied by a set of highly delocalized unoccupied states with oscillating nodal structures, readily accessible under low-bias transport measurements. In contrast, the Ag+-coordinated nanowires exhibit weak spin-flip scattering that is more than an order of magnitude smaller than spin-preserving transport. This duality establishes the choice of coordination metal as a decisive parameter to govern metal-metal interaction, electron delocalization, and spin-dependent transport. Overall, our findings demonstrate how relativistic effects and quantum confinement intersect in these bio-templated, quasi-one-dimensional molecular conductors.