Cavity-mediated enhancement of CISS in DNA junctions

Abstract

Using a model of the double-stranded DNA junction, we employ a nonequilibrium Green's function (NEGF) approach to theoretically study the chiral induced spin selectivity (CISS) effect both outside and inside the molecular cavity. We demonstrate that outside the cavity, spin polarization is sensitive to gate voltage, and we explain this sensitivity through the alternating character of DNA molecular orbitals. Inside the cavity, we show a 6 to 8 times increase in spin polarization and argue that this enhancement arises from the non-uniform distribution of escape rates among molecular orbitals, resulting in better and worse conducting channels. This, combined with the alternating character of the molecular orbitals, elucidates why electron population redistribution among the channels, induced by coupling to the cavity mode, leads to a change in spin polarization. We hope that experimental verification of the proposed polarization enhancement will occur in the near future.