Spin filtering through circular DNA molecular junctions: External field vs chirality.

To gain an in-depth understanding of the so-called Chiral-Induced Spin Selectivity effect in helical molecular chains, we developed a spin-orbit interaction model in second-quantized form to describe the circular helical structure. We then employed the standard non-equilibrium Green's function theory to study spin filtering through circular DNA molecular junctions and found the general spin-dependent sideband resonance structure in conductance. By utilizing the natural structure of circular DNA molecules, we further demonstrated the unique spin-filtering Aharonov-Bohm effect of non-magnetic systems and the relationship between spin polarization, external fields, and chirality. The existence of a critical transverse electric field in the modulation of the spin-filtering Aharonov-Bohm effect is especially very interesting and inspiring.