Emergent paramagnetism of DNA molecules

Abstract

We investigate the magnetic properties of the DNA molecules, especially associated with electronic orbital motions. Based on an empirical model describing the electronic properties of DNA molecules, it is shown that both $A\text{\ensuremath{-}}\mathrm{DNA}$ and $B\text{\ensuremath{-}}\mathrm{DNA}$ manifest paramagnetic response at zero temperature. However, the paramagnetic component for $A\text{\ensuremath{-}}\mathrm{DNA}$ is shown to be too weak to dominate diamagnetism of atomic spins, and the overall response becomes diamagnetic. Furthermore, investigating the band-gap effects on the temperature dependence of magnetization, we suggest that the fast decay of the paramagnetic component is a clue for the absence of gap in molecular energy levels of wet DNA.